PC 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 & 11Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteTo test your laptop’s Ethernet speed, check the negotiated link rate first, then measure throughput to another device on your local network. An internet speed test is useful for checking your overall connection, but it cannot tell you by itself whether the laptop’s Ethernet link, router, or internet service is limiting performance.
What an Ethernet speed test actually measures
Your negotiated Ethernet link rate is the speed agreed between the laptop’s network adapter and the device at the other end of the cable, usually a router or switch. It describes that local connection, not the speed you will necessarily get from an internet download.
An internet speed test measures an end-to-end path. Its result also depends on the router and modem, your ISP service, the test server, other traffic on your network, and conditions along the internet route. Treat it as an observation of the whole connection—not a diagnosis of the laptop’s Ethernet link.
For a useful diagnosis, compare three things: the negotiated link rate, throughput between two devices on your local network, and internet speed-test results. Record the laptop model and OS, Ethernet adapter, cable, router or switch port, and ISP plan. Pause large downloads and other heavy network activity, and repeat tests under similar conditions.
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#1 Best Overall
- Multifunctional Network Cable Tester: TESMEN TLP-123A Supports RJ45 and RJ11, enabling rapid detection of line connectivity, short circuits, open circuits, miswiring, and cable shielding status. An essential tool for troubleshooting line faults and network maintenance, it effectively boosts your work efficiency
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- What you will get: 1 * TLP-123A Network Cable Tester, 1 * user manual, 2 * AAA batteries
How to check whether Ethernet is running at 100 Mbps or 1 Gbps
On a Mac
- Open System Settings > Network.
- Select the Ethernet service. Its name may include the adapter’s manufacturer or model.
- Choose Details > Hardware and inspect the configuration and available speed choices.
Apple recommends leaving the settings automatic unless a network administrator provides specific values. Manually forcing speed or duplex settings can cause performance problems if they do not match the connected equipment. See Apple’s Mac Gigabit Ethernet guidance and Apple’s Ethernet hardware-options guidance.
On Windows
Open Settings > Network & internet and inspect the Ethernet connection status. Windows versions and network-adapter drivers do not all expose negotiated link speed in the same place, so consult the adapter manufacturer’s current documentation or its properties if you need the precise rate. Microsoft’s Windows Ethernet troubleshooting guidance covers status and connection checks, but does not establish one universal link-rate display path for every PC.
Rank #2
- VERSATILE CABLE TESTING: Cable tester for data (RJ45) terminated cables and patch cords, ensuring comprehensive testing capabilities
- LARGE BACKLIT LCD: Backlit LCD display enables easy reading of pin-to-pin wiremap results, even in low-lit areas
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- MULTIPLE TONE GENERATOR STYLES: Tone on a single wire, wire pair, or all 8 conductor wires using the multiple style tone generator (solid/warble); requires probe Cat. No. VDV500-123 (sold separately)
How to measure throughput on your local network
A local test helps separate the laptop-to-network-device path from the ISP and the wider internet. One option is iPerf3, a client-server tool that measures throughput between two devices. You need a second computer connected to the same router or switch; a speed test to an internet server is not a substitute.
- Install iPerf3 on the second computer and start it in server mode.
- Find that computer’s local IP address and use it as the server address from the laptop.
- Run the laptop as the iPerf3 client. Repeat the test, and test in the other direction if that is relevant to your setup.
- Keep the test conditions consistent. iPerf3 supports timed tests, reporting intervals, TCP or UDP testing, and parallel streams; change one option at a time if you are comparing results.
Consult the iPerf3 documentation for client/server use and available test options. The result applies to the path between those two devices. It does not measure the ISP’s entire service or prove which component is responsible for a low result. A difference between one stream and multiple parallel streams can indicate a path or host-configuration limit, but it does not identify a unique cause on its own.
Rank #3
- VERSATILE CABLE TESTING: Cable tester tests voice (RJ11/12), data (RJ45), and video (coax F-connector) terminated cables, providing clear results for comprehensive testing on unenergized Ethernet cables (not designed to test PoE)
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- COMPREHENSIVE FAULT DETECTION: Test for Open, Short, Miswire, or Split-Pair faults, ensuring thorough fault detection and identification
- BACKLIT LCD DISPLAY: Backlit LCD screen displays cable length, wiremap, cable ID, and test results, ensuring easy readability in various lighting conditions
- EFFICIENT CABLE TRACING: Trace cables, wire pairs, and individual conductor wires using the multiple style tone generator (requires analog probe Cat. No. VDV500-123, sold separately), simplifying cable tracing tasks
How to find the bottleneck
Use the link-rate reading, local throughput, and internet test together. These patterns are clues for the next check, not proof of a single cause.
- Low link rate and low local throughput: Check whether the cable is fully seated or damaged, whether the cable and adapter support the expected rate, and whether the laptop and router or switch ports can negotiate it.
- Expected link rate but low local throughput: Check adapter or driver settings, host load, router or switch configuration, test setup, and other network traffic.
- Strong local throughput but weak internet results: Look beyond the laptop’s local Ethernet path: check the router’s WAN connection, modem, ISP service, congestion, VPN or security software, test server, and other internet-path factors.
- A second laptop or adapter performs better on the same cable and port: That shifts suspicion toward the original laptop, adapter, or its configuration. Microsoft recommends comparing another PC as one way to narrow down where the issue lies.
Change one component at a time and repeat the same test. For example, keep the laptop and port fixed while swapping the cable; then keep the cable fixed while trying another port. This makes each comparison more useful.
Rank #4
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- Fast/Slow Mode with LED Indicators: Switch between fast and slow scan speeds to identify wiring issues more precisely. LED lights on both master and remote units show wire order, making it easy to spot errors like open pairs or misaligned pins at a glance.
- Split-Type Design for Long-Distance Testing: Master and remote units can be detached and used separately, allowing you to test both ends of a long cable run, ideal for wall-mounted ports, long runs, or structured cabling. Perfect for home, office, or professional IT setups.
- Compact, Lightweight & Durable: Ergonomically designed with sturdy ABS housing, this pocket-sized tester is ideal for on-the-go network engineers, DIYers, and electricians. It’s your go-to toolkit for cable maintenance, upgrades, or new installations.
- Safe & Easy to Use: Simple one-button operation makes testing quick and hassle-free. LED indicators clearly show wiring status, while the G light instantly identifies shielded (FTP/STP) or unshielded (UTP) cables. Supports safe testing of telephone lines with typical voltages under 48-72V, ideal for both home and professional use.
Check the cable, adapter, and network ports
Inspect and swap the cable
Check both ends for a secure fit and inspect the cable for damage. Try a known-good cable before buying a replacement, and test another router or switch port if one is available. If the computer and connected device support Gigabit Ethernet but the cable does not, Apple says a cable that supports Gigabit Ethernet may be needed. That is a reason to test a suitable cable—not a reason to assume every slow connection needs an upgrade.
Apple also recommends inspecting connections and settings and restarting the Mac and Ethernet device when troubleshooting. See its Ethernet connection troubleshooting guide.
Best Value
- EASY WIRE TRACING: Simple analog tone generator and wire tracing probe for open-ended, non-active low-voltage wires, making wire tracing hassle-free (<60v)
- OPTIMIZE SIGNAL FOR BEST RESULTS: Separate wires when possible and use proper grounding to improve tone detection and accuracy
- ALLIGATOR CLIPS INCLUDED: Comes with alligator clips for easy connection to unterminated wires, providing convenience during testing
- RJ45 TO RJ45 TEST CABLE: Includes an RJ45 to RJ45 test cable for seamless connectivity during testing and wire mapping
- COMPREHENSIVE WIRE MAPPING: Toner and probe together perform a pin-to-pin wire map test, ensuring thorough wire mapping and identification
Check the adapter and both ports
Confirm that the laptop adapter and the router or switch port support the rate you expect. A built-in Ethernet jack is only one part of the path: the adapter, cable, and connected port all need to support the intended rate. A USB-to-Ethernet adapter cannot overcome a slower port or a limitation elsewhere in the connection.
If your laptop lacks an Ethernet jack, Apple notes that a Mac can use a USB-to-Ethernet adapter or a Thunderbolt-to-Gigabit-Ethernet adapter. When choosing an adapter, match its connector and host interface (such as USB-A, USB-C, or Thunderbolt) to the laptop, and check operating-system support and the adapter’s supported Ethernet rate. Confirm that the router or switch port supports that rate as well.
Why Ethernet may be slower than your internet plan
The plan’s advertised service rate and a laptop’s measured internet throughput are different kinds of information. A weak internet result can come from the router’s WAN connection, modem, ISP service, congestion, test server, VPN or security software, or activity elsewhere on the network—even when the laptop’s negotiated Ethernet rate and local throughput are healthy.
Run more than one reputable internet speed test and record download, upload, latency, and the time of each test. Compare those results with a local iPerf3 test and, if possible, a second device using the same cable and port. If the local test is strong but internet results are weak, focus on the internet path rather than replacing the laptop’s Ethernet cable or adapter without further evidence.
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