How to check speeds through a powerline adapter

Your internet feels slow in a room connected through a powerline adapter, but it is hard to tell whether the adapter, your internet service, or another device is responsible. A speed test can show how the connection performs, but you need a direct Ethernet comparison to judge the adapter fairly.

Use the same computer, cable, and Speed Test for both measurements. This gives you a useful comparison of download speed, upload speed, ping, and jitter without treating the adapter’s advertised rate as its real-world speed.

Compare the powerline adapter with direct Ethernet

Open the Speed Test on the computer you will use for both checks. Pause downloads, video streams, cloud backups, and other activity that could use your connection.
Connect the computer directly to the router with an Ethernet cable. If the computer has Wi-Fi, turn it off for this comparison so the test uses the cable. Run the speed test and note download, upload, ping, and jitter.
Connect one powerline adapter to the router with Ethernet, and the other to the computer with Ethernet. Plug each adapter directly into a wall outlet. Keep the same computer, Ethernet cable, browser, and test page, then run the test again.
Run each setup three times, alternating between direct Ethernet and powerline if it is practical. Write down each result. The middle reading from the three runs is a helpful comparison when one test is unusually high or low.

For a fair test, keep other network activity similar and avoid testing one setup during a busy household period and the other when everyone is offline. Speed tests use test data exchanged with a server, so results can also vary with server load and internet traffic.

What the results mean

Powerline is consistently slower than direct Ethernet

If download or upload speed is lower through the adapters in all or most runs, the powerline path is limiting the connection. A much slower result can matter for large downloads and video uploads. A modest difference may not be noticeable for browsing or email.

Both setups are similarly slow

The adapter is less likely to be the main cause if direct Ethernet and powerline produce similar results. Your internet plan, router, internet provider, or activity elsewhere on the network may be limiting the test. Compare the result with the speed your plan promises, while remembering that advertised plan speeds are not a guarantee for every test.

Speed changes a lot between runs

Large swings can point to changing network activity, a busy test server, or electrical interference affecting the powerline link. Compare the two setups at the same time and repeat the test after pausing other downloads. A low result from one run alone does not prove the adapter is faulty.

Download looks fine but upload is low

Check whether your plan provides a lower upload speed than download speed. If direct Ethernet has a noticeably better upload result, the adapter path or its connection to the router may be restricting uploads.

Ping or jitter rises through powerline

Ping is the time a small request takes to reach the test server and return. Jitter is the variation in that response time. Higher or less steady readings through the adapters can affect calls and online games even when download speed seems adequate.

How to improve the connection

Plug both adapters into wall outlets. Power strips, surge protectors, and some extension cords can interfere with the signal. Try a different wall outlet if the first one gives a weak or inconsistent result.
Make sure the computer is using Ethernet. Turn off Wi-Fi during the test, or confirm that the computer is connected through the adapter. On Windows 11, check Settings › Network & internet › Ethernet. On macOS, check System Settings › Network › Ethernet.
Check the Ethernet cables and ports. Reseat each cable and try a cable you know works. A damaged cable or a limited Ethernet port can hold down the result even when the powerline link is good.
Try another pair of wall outlets. Powerline performance depends on the home’s wiring and the route between outlets. Outlets in different rooms or on different electrical circuits may perform very differently.
Reduce competing network traffic. Pause large downloads, backups, and streaming on other devices, then repeat both measurements. This helps separate adapter performance from congestion on your home network.
Check the adapter maker’s setup instructions. If the adapters have a pairing or reset process, follow the instructions for your model. Avoid assuming that a reset will improve speed, since it can remove the connection between the paired units.

When the adapter may be faulty

Test the same adapters and cables in another pair of outlets, then compare them with a direct Ethernet connection again. If one adapter repeatedly disconnects, fails to pair, or performs far worse than the same setup in another location, it may be damaged. But poor results that follow one room or outlet are more likely to reflect the wiring or electrical interference than a failed adapter. Contact the manufacturer if the units are under warranty, or consider another network connection method if that room’s wiring consistently gives poor results.

Why the advertised speed is not your test result

Powerline packaging may show a link rate measured between the adapters, not the amount of internet data your computer can download. Real throughput is affected by electrical wiring, outlet placement, interference, adapter ports, and your internet service. The Speed Test measures the whole route from your computer to its test server, so it cannot isolate the adapter’s maximum local speed by itself.

Use the direct Ethernet result as a baseline, not as a promise of the speed every device or website will reach.