Recommended Free Tools
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
If Ethernet is not working, a failed LAN card is only one possible cause. First test the cable and router or switch port, then check whether the problem affects other devices. If the fault is limited to one computer, inspect its Ethernet adapter and driver before considering replacement.
First determine whether the problem is the computer or the network
Check whether other devices can connect through the same router or switch. If they also fail, investigate the router, modem, or internet service; if another computer works on the same network, focus on the original computer and its wired connection. Microsoft recommends this comparison as an early way to narrow down Ethernet problems.
Also distinguish “Ethernet connected but no internet” from “no Ethernet link.” A local connection can be established while the router, modem, or internet service has a separate problem.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Check the cable and network port
- Make sure the Ethernet cable is firmly seated at both ends.
- Confirm the router end is plugged into a LAN port, not the Internet or WAN port.
- Try another known-good cable, then try a different LAN port on the router or switch.
- If practical, test the same cable and port with another computer or wired device.
Microsoft recommends checking the cable and router port and trying another cable. Apple also advises checking external device power and cabling. If the link indicator is off, that alone does not establish that the computer’s LAN card has failed: the cable, connector, network port, adapter state, or other device at the other end may be responsible. Lenovo’s controller guidance likewise lists the cable, connector, and switch among possible causes of an unlit indicator.
#1 Best Overall
- 2.5 Gbps PCIe Network Card: With the 2.5G Base-T Technology, TX201 delivers high-speeds of up to 2.5 Gbps, which is 2.5x faster than typical Gigabit adapters. Performance varies by conditions, distance to devices, and obstacles such as walls
- Versatile Compatibility – The Ethernet Network Adapter is backwards compatible with multiple data rates(2.5 Gbps, 1 Gbps, 100 Mbps Base-T connectivity). The 2.5G Ethernet port automatically negotiates between higher and lower speed connection.
- QoS: Quality of Service technology delivers prioritized performance for gamers and ensures to avoid network congestion for PC gaming
- Wake on LAN – Remotely power on or off your computer with WOL, helps to manage your devices more easily
- Low-Profile and Full-Height Brackets: In addition to the standard bracket, a low-profile bracket is provided for mini tower computer cases
A lit link indicator is not proof that network traffic is working correctly. Intel notes that a link light can be on even when communication with the other end has not been properly established.
Check whether the computer detects its Ethernet adapter
Windows
Open Device Manager and expand Network adapters. Look for the Ethernet adapter and check whether it is disabled or reporting a problem. If it is missing or malfunctioning, consult the computer manufacturer’s support information for the exact model and its recommended driver. Adapter names and driver steps vary by hardware.
Rank #2
- Ultra-Fast: 10/100/1000Mbps PCIe Adapter upgrade your Ethernet speed to Gigabit
- Automation: Wake-on-LAN supporting Auto-Negotiation and Auto MDI/MDIX
- Supports: IEEE802.3x Flow Control for Full-duplex Mode and backpressure for Half-duplex Mode; 4k Bytes Port: 1x 10/100/1000Mbps RJ45 Network Media
- Compatibility: Windows 11, 10, 8.1, 8, 7, Vista, XP
- Dual Bracket: Low profile and standard profile bracket inside works with both mini and standard size PCs.
Microsoft’s Windows Ethernet guidance also recommends running the network troubleshooter. In Windows 11, the current troubleshooting flow uses Get Help; Microsoft’s page includes steps for older Windows versions as well. If a driver must be reinstalled and the computer has no internet access, Microsoft advises downloading the appropriate driver on another computer and transferring it. Prefer the matching computer-maker driver over generic third-party driver downloads.
Mac
Check network settings for the Ethernet service and the status of any external Ethernet adapter. For external networking devices, Apple recommends checking that the device has power, inspecting the cable and indicator lights, and restarting equipment in sequence from the internet-facing device toward the Mac.
Rank #3
- 10 Gbps PCIe Network Card: With the latest 10GBase-T Technology, TX401 delivers extreme speeds of up to 10 Gbps, which is 10× faster than typical Gigabit adapters, guaranteeing smooth data transmissions for both internet access and local data transmissions[1]
- Versatile Compatibility: With extreme speed and ultra-low latency, 10GBase-T is backwards compatible with multiple data rates (10 Gbps, 5 Gbps, 2.5 Gbps, 1 Gbps, 100 Mbps), automatically negotiating between higher and lower speed connections
- QoS: Quality of Service technology delivers prioritized performance for gamers and ensures to avoid network congestion for PC gaming
- Free CAT6A Ethernet Cable: To maximize TX401's performance, a 1.5 m CAT6A Ethernet Cable is included—rated for up to 10 Gbps while a regular cable is only rated for 1 Gbps
- Low-Profile and Full-Height Brackets: In addition to the standard bracket, a low-profile bracket is provided for mini tower computer cases
A Mac without a built-in Ethernet port can connect through a compatible USB or Thunderbolt Ethernet adapter. Apple describes both USB-to-Ethernet and Thunderbolt-to-Gigabit-Ethernet options; confirm that an adapter suits the Mac’s connector and the required network speed.
Understand Ethernet link speed before judging performance
The Ethernet link speed shown by an operating system or device is the negotiated rate between the computer’s adapter and the router or switch. It is not an internet speed test and does not tell you how fast data can travel through your internet connection.
Rank #4
- Unparalleled 5 Gbps Speed: Future-proof your desktop PC's wired connection with the 5 Gbps PCIe network card. It takes your connectivity to the next level with speeds 5 times faster than a typical Gigabit PCIe Ethernet card
- Hyper-Fast Internet Access: Experience boosted speed, reduced latency, and enhanced responsiveness with the PCIe network card, making your computer ideal for intense gaming and flawless streaming. Harness your ISP's speeds with added 5GBASE-T technology
- Instant Local Network Transfer: Whether integrated into your client PC or host server, the PCI Express network card establishes lightning-fast connections with other devices in your local network, elevating the efficiency of data transmission
- Crafted for Maximum Reliability: Enhanced with dense fins and high-quality aluminum construction, the PCIe nic optimizes heat dissipation, ensuring consistent performance and reliability
- Supports Windows 11 / 10 / Windows Server 2022: Simply install the driver from the included disc or download it from our website to achieve the full 5Gbps speed. Supports Wake on LAN and QoS
TP-Link’s instructions explain how to view this negotiated rate on Windows and Mac and emphasize the distinction from internet throughput. If the displayed link rate is lower than expected, check the capabilities and settings of both devices and the cable. Intel’s advice about adapter properties and cable type applies specifically to Intel Ethernet adapters, not every network card.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsDo not conclude that the LAN card is faulty solely because an internet speed test is slow. A low test result and a low local link rate are different clues and should be investigated separately.
Best Value
- 2.5 Gbps Next-gen Connection: Unleash extreme speeds on your desktop PC with this 2.5 Gb PCIe network card. It boosts your connectivity to new heights by delivering 2.5x faster speeds than a typical Gigabit PCIe network adapter
- Ultra-fast Internet Access: With a boost in speed, latency and responsiveness, this PCIe ethernet card lets you win every gaming battle and enjoy flawless streaming. Harness the latest 2.5 GBASE-T technology to make the most of your Internet speeds
- Instant Local Network Transfer: Whether incorporated into your client computer or host server, it builds a blazing-fast connection with other devices in your local network. Elevate local data transmission with this PCIe Ethernet card
- Durable Metal Shielding: Reduces electromagnetic interferences and improves stability and reliability for every connection. Excellent heat dissipation also ensures a longer lifespan for this PCIe nic
- Latest Realtek Chip: Works with various systems, including Windows 11/10/8.1/8/7, Windows Server 2022/2016/2012 R2/2012/2008 R2/2008/2003 and Win XP/Vista/2000. Supports Wake on LAN
Use substitution to test the computer’s Ethernet port
If the cable and router port work with another device but the original computer still cannot connect, try a different network path if one is available. A compatible USB-to-Ethernet adapter can provide a useful cross-check: if it works on the same computer and network, the onboard Ethernet connection becomes a stronger suspect, though it does not by itself identify the exact fault.
Choose an external adapter by its host connector, operating-system support, and maximum Ethernet link speed. If a desktop’s onboard port remains undetected or cannot establish a link using known-good network equipment, ask the computer or motherboard manufacturer about model-specific diagnostics and repair options. Consider hardware replacement only after checking the cable, port, adapter configuration, and driver.
Windows version and support status
Microsoft states that Windows 10 support ended on October 14, 2025. Its Ethernet troubleshooting page still includes Windows 10 steps, but that does not change the operating system’s support status.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Quick Recap
Sources
- Microsoft Support: Fix Ethernet connection problems in Windows
- Intel: How to troubleshoot Intel Ethernet Adapters Gigabit speed issues?
- Apple Support: Troubleshoot external networking devices on Mac
- Apple Support: Connect your Mac to the internet using Ethernet
- TP-Link: How to Check Ethernet Speed on Windows and Mac (updated July 6, 2026)
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.
