@Riffraff81 

I have a similar issue with XFinity where I'm only getting half the speed that I'm paying for (2GB DL for me). I'm also on Windows 11 on a desktop PC built at the end of 2024. I've narrowed it down to the TP-Link TX201 2.5GBE adapter, software drivers from both TP-Link and Realtek, and the CAT6 ethernet cable. Here are some of the troubleshooting steps I took:

1) In Win11, go to Settings > System > Network & internet > Ethernet

1a) Scroll down until you see Aggregated link speed (Receive/Transmit)

- Mine says 1000/1000, and I've installed the latest software drivers from TP-Link (as of today 11 July 2025) and the lastest drivers from Realtek as well. I'm stuck at 1000/1000 even though my modem/gateway gets 2GB download speed.

2) Using the XFinity app (sorry), at the bottom of the app, press Services

2a) Find Internet > Troubleshoot > Test your whole home network (this will test the speed of your modem/gateway)

- Since you're getting almost 1GB on your other devices, this is just a routine check of the cable modem/gateway). I get around 700MBs on my other devices, but I have an older phone and tablet. By using the app, it will show its testing results in real time so you can see the speeds.

3) Re-seat the TX201 in a different PCI-E slot. I only had 2 other available slots, but both got the same results.

It's frustrating that I've now spent hours trying to get the adapter to work after reading that others who have purchased this same NIC had theirs worked at 2.5GB within minutes of installation. I'm sure you're even more frustrated not even getting 1GB. I wish you the best of luck in getting a resolution.