iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Quick answer: A correctly operating Openreach FTTP optical network terminal (ONT) has a solid green PON light, no LOS warning, and a network link to your broadband router. A flashing or unlit PON, a red LOS light, or no lights indicates a power, Ethernet, optical-network or provisioning problem. Check the ONT and router power, reseat the Ethernet cable, test more than one device, restart the ONT for 30 seconds, and use the documented reset only if necessary. If the fault remains, your broadband provider—not you—must run service tests and escalate to Openreach.
What the Openreach ONT lights mean
The wall-mounted ONT converts the fibre signal entering your property into an Ethernet connection for your broadband provider’s router. Its LEDs identify which part of the connection is failing. Read the lights before changing settings or replacing equipment, because the same “no internet” symptom can come from a dead power supply, a loose router cable, a Wi-Fi problem, an optical fault or an activation that has not yet completed.
| ONT indication | What it normally means | What to do |
|---|---|---|
| Power on, solid green PON, LOS off | The optical connection is in its normal state. Openreach describes this as working properly. | Check the router, WAN/FTTP port, authentication and individual devices. If all devices are offline, ask your provider to test the service. |
| Flashing PON | The ONT is not in a stable optical connection state. Openreach’s self-install guidance treats a persistent flashing PON as a possible connection issue. | Check power, leave the fibre untouched, restart the ONT once, then report the continuing condition to your provider. |
| PON off | The homeowner guidance identifies this as a possible network issue. | Confirm the ONT has power. If PON stays off, give the exact light state to your provider. |
| Red LOS | Loss of service or an optical-path problem. | Do not open, clean or repair the fibre. Contact the provider for diagnosis and escalation. |
| No lights | The ONT may not be receiving power, or the unit may have failed. | Check the mains plug and power supply. If the lights cannot be restored, report it; an engineer may be required. |
| Solid LAN together with solid PON | The ONT has an Ethernet link to the router. In an official setup transcript, Openreach engineer Joe says this combination means you are “connected and ready to go.” | If browsing still fails, investigate the router, service login/provisioning or Wi-Fi rather than the optical light first. |
LED labels and colours can vary slightly by ONT model, but the fault boundaries remain useful: power and lights concern the ONT, LAN concerns the router cable, and internet access beyond that point belongs to the router or provider service.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Before you troubleshoot: identify the equipment and timing
Find the ONT and router
The ONT is usually a small wall-mounted box installed where the fibre enters the property. It is separate from the broadband provider’s router. A short Ethernet cable should run from the ONT’s LAN/Ethernet socket to the router port designated by the provider as WAN, Internet or FTTP. Do not confuse that cable with the thin optical fibre entering the ONT.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Check the agreed activation date
Openreach says the communications provider agrees an activation date and that Full Fibre service should be activated before midnight on that date. During the installation window, an apparently inactive service can therefore be normal. If the date has not passed, complete the checks below but do not assume the fibre is faulty solely because the router has no internet yet. If the date has passed, the provider owns the support conversation and must escalate to Openreach when its tests show an Openreach-side issue.
Allow for the installation window
Openreach states that most installations take between one and four hours. That is a published general estimate, not a guarantee for every property or appointment. Keep the ONT and router accessible and powered while work is being completed, and avoid moving the wall-mounted equipment.
Step 1: check power without disturbing the fibre
- Confirm the ONT power adapter is firmly connected to the ONT and to a working mains socket.
- Confirm the broadband router is also connected to mains power and switched on.
- Where possible, use the main wall socket rather than an overloaded extension or switched-off power strip.
- Look for the ONT’s power light. If there is no power indication, test the socket with another appliance and reseat the adapter.
- Do not pull, bend, disconnect or attempt to clean the optical fibre. Openreach advises avoiding unnecessary unplugging or movement of the wall-mounted unit.
If the socket works but the ONT still has no lights, tell the provider exactly that. A no-light condition can require an engineer; it is not fixed by changing Wi-Fi settings.
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchPC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Step 2: read every ONT light and record the state
Write down the status before restarting anything. Include whether each light is off, solid or flashing, and its colour. For example: “Power solid green, PON flashing green, LOS red, LAN off.” This wording gives the provider useful information and prevents a vague “the box is broken” report.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
- Solid green PON and LOS off: the optical side is in the normal state. Continue with Ethernet, router and device checks.
- Flashing PON: allow the ONT to complete its startup, then perform one restart. If it continues flashing, report it rather than repeatedly resetting.
- PON off: verify power and report a persistent off state as a possible network issue.
- Red LOS: treat this as optical loss. Fibre repair is an Openreach/provider job.
- LAN off: the ONT may not detect the router cable, the cable may be damaged, or the router’s designated port may be wrong.
- LAN solid with PON solid: the physical ONT-to-router link exists, so test the router and service configuration.
Step 3: verify the Ethernet connection to the router
- Locate the Ethernet lead between the ONT and router.
- At the ONT, unplug the connector and insert it again until the locking tab clicks.
- Repeat at the router end. Use the router’s WAN, Internet or FTTP port specified by your provider, not an ordinary LAN port unless the router instructions explicitly require it.
- Inspect the cable for crushed sections, broken clips or loose plugs.
- If you have one, try a known-good replacement Ethernet cable of the same type. A spare FTTP router cable can solve a damaged, loose or missing router link, but it cannot correct a red LOS or persistent flashing PON.
- Check whether the LAN light appears after reseating the cable. Give the provider the result.
If another compatible router is available, connect it according to the provider’s instructions. If the second router obtains service, the original router or its configuration is the likely fault. Do not change provider authentication settings at random; some services require specific credentials or automatic provisioning.
Step 4: restart the ONT in the documented order
A restart clears a temporary startup or link condition without changing the service configuration.
- Switch the ONT off at its power source.
- Wait a full 30 seconds.
- Switch it back on and allow the lights time to settle.
- Check PON, LOS and LAN again, then test the router.
Do not repeatedly power-cycle the unit every few seconds. If the PON remains flashing, LOS remains red, or the ONT remains dark after this restart, move to the reset procedure once and then contact the provider.
Recommended Free Tools
Step 5: use the ONT reset only when the fault persists
The small reset button is normally recessed. Use a paper clip or SIM-eject tool; do not insert a sharp object into any optical or Ethernet socket.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
- Locate the reset button on the ONT.
- Press and hold it for approximately 10–15 seconds, until the lights go out.
- Release the button.
- Wait for the ONT to boot fully and for the indicators to settle.
- Reconnect or reseat the Ethernet lead if necessary, then test the router and two devices.
A reset is not a substitute for an optical repair or provider activation. If the same light pattern returns, stop resetting and report the exact sequence. Excessive resets can make it harder to describe the original fault and will not repair a damaged fibre path.
Step 6: separate an FTTP fault from Wi-Fi or device trouble
Test more than one device
Connect two different devices to the router. If only one phone, laptop or television fails, the FTTP line may be healthy; investigate that device’s Wi-Fi, network profile, VPN, browser or adapter. If every device fails, continue with the router and provider checks.
Use a wired test when possible
Connect a computer to a normal router LAN port with Ethernet, following the router maker’s instructions. A wired connection bypasses wireless interference and range problems. If wired internet works while Wi-Fi does not, the fibre service is operating and the issue is confined to wireless settings or coverage.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Interpret a normal ONT with no internet
When PON is solid, LOS is off and LAN is present but all devices are offline, ask the provider to check router configuration, authentication and service provisioning. Openreach directs customers to their communications provider because the provider can run the required line and service tests and arrange escalation.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Why a PON light may keep flashing
A flashing PON means the ONT has not reached a stable optical state. The cause can be a connection problem in the fibre network, an installation that has not completed, or a temporary startup condition. Customer actions are limited to confirming power, performing one restart and, if needed, the documented reset. Do not disconnect the optical lead, bend it sharply, open the ONT or attempt to clean the fibre end. Persistent flashing after the checks belongs with the provider.
What a red LOS light means
LOS stands for loss of signal. A red LOS indicator means the ONT is not receiving the expected optical service. It is different from a Wi-Fi password problem and cannot be repaired with a replacement Ethernet cable or a new router. Keep the ONT powered, record the time and light pattern, and contact the provider. The provider can determine whether the fault is inside the property, in the local Openreach network or related to provisioning, then arrange the appropriate work.
What to do when there is no internet after installation
- Check whether the agreed activation date has arrived and whether midnight on that date has passed.
- Confirm ONT and router power.
- Record PON, LOS and LAN states.
- Reseat the ONT-to-router Ethernet cable and confirm the correct WAN/FTTP port.
- Try a second device and, if possible, a wired connection.
- Restart the ONT for 30 seconds.
- Use the recessed reset for 10–15 seconds only if the condition persists.
- Call the provider with the activation date, light pattern, restart result and device-test result.
If the ONT lights are normal but the provider says the line is active, ask it to verify the router’s service credentials or automatic configuration. If the lights show optical loss, ask for an Openreach escalation rather than buying additional networking equipment.
Activation delays: who is responsible and when to call
Openreach’s process places the activation commitment with the communications provider. The provider should give you the agreed date and related communications. Openreach says the service should be active before midnight on that date; if it is not, contact the provider as soon as that window has passed.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
When you call, provide:
- the address and account details requested by the provider;
- the agreed activation date;
- the exact time you checked;
- every ONT light’s colour and state;
- whether the Ethernet LAN light appears;
- whether two devices and a wired test failed;
- whether you completed a 30-second restart and the 10–15-second reset.
The provider should run service and line tests and escalate to Openreach when appropriate. You do not need to arrange an Openreach escalation independently, and an engineer cannot be meaningfully dispatched without the provider’s fault record.
Decision table: choose the next action from the symptoms
| Observed condition | Likely fault domain | Customer action | Escalation |
|---|---|---|---|
| No ONT lights | Power supply or ONT hardware | Check mains socket and adapter; avoid moving the unit. | Provider; an engineer may be needed. |
| Red LOS | Optical network or fibre path | Keep powered; do not open or repair fibre. | Provider escalates to Openreach. |
| PON flashing after restart/reset | Optical connection or provisioning | Record the state and stop repeated resets. | Provider diagnosis and escalation. |
| PON off with power on | Possible network issue | Check power, then report the persistent state. | Provider. |
| PON solid, LOS off, LAN off | Ethernet cable, router port or router hardware | Reseat cable, try a known-good cable and verify WAN/FTTP port. | Provider if the link will not establish. |
| PON and LAN solid, one device offline | Device or Wi-Fi issue | Test another device and review that device’s network settings. | Device or router support if needed. |
| PON and LAN solid, every device offline | Router configuration, authentication or provisioning | Try a wired test and restart the router as instructed by the provider. | Provider service tests. |
| Internet absent before agreed date | Activation not yet due | Keep equipment powered and complete basic checks. | Provider if the appointment changes or instructions are unclear. |
| Internet absent after midnight on agreed date | Activation or service fault | Quote the date and report the light state. | Provider owns escalation to Openreach. |
What not to do
- Do not remove the ONT when moving home. Openreach records its serial number against the property, and the unit will not work at another address. Leave it mounted and powered for the next occupant.
- Do not open the optical connection. Fibre components are not a user repair, and attempts to clean or reconnect them can create a new fault.
- Do not buy a router to cure red LOS. A different router cannot restore a missing optical signal.
- Do not treat a cable as a cure-all. A replacement Ethernet lead is relevant only when the ONT-to-router link is loose, damaged or missing.
- Do not keep resetting indefinitely. One restart and one documented reset provide useful information; persistent symptoms need provider testing.
Moving house with an Openreach FTTP service
Leave the wall-mounted ONT at the property. Its serial number is associated with that address, so taking it with you will not provide service at the new home and can leave the original property without its installed equipment. Tell your provider that the ONT remains in place when arranging the move, and follow the new address’s activation instructions separately.
How to report the problem efficiently
A concise report helps the first-line agent choose the right test. Use a description such as:
Free tools Windows power users keep installed
One-click scans. No signup required.
“My agreed FTTP activation date was [date]. The ONT power light is [state], PON is [state/colour], LOS is [state/colour], and LAN is [state]. I reseated the Ethernet cable in the WAN/FTTP port, tested two devices, restarted the ONT for 30 seconds and held reset for 10–15 seconds. The result is unchanged.”
Replace the bracketed words with your actual details; do not quote a diagnosis you have not observed. Ask for the provider’s fault reference and the next update time. If the provider says the optical network is not responding, confirm that it will escalate to Openreach rather than asking you to purchase more equipment.
When a replacement Ethernet cable is worthwhile
A spare cable is a sensible, limited remedy when the Ethernet plug will not latch, the cable has visible damage, the LAN light stays off after reseating, or the cable is missing from a self-install kit. Use it only between the ONT and the provider router, and verify the router’s designated WAN/FTTP socket. If PON is flashing, PON is off or LOS is red, the cable is not the root cause; retain the existing setup and contact the provider.
Quick Recap
Summary checklist
- Normal optical state: solid green PON and LOS off.
- Power both ONT and router from working mains sockets.
- Record every light as off, solid or flashing and note its colour.
- Reseat both Ethernet ends in the correct ONT and router ports.
- Try a known-good cable only for an Ethernet-link suspicion.
- Test two devices and, if possible, one wired connection.
- Restart the ONT for 30 seconds; reset for 10–15 seconds only if the fault remains.
- Do not touch the optical fibre or remove the ONT when moving.
- After the agreed activation date, contact the broadband provider; it owns testing and Openreach escalation.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →
