Slow internet over 5Ghz all of a sudden

illuvattarr

Reputable
Dec 19, 2014
13
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4,510
Since yesterday I am experiencing very slow wifi internet speeds on my desktop PC with Windows 10. I didn't change anything in my setup and a few days ago, it was blazingly fast. I noticed it because I often use my PC to stream videos (also 4K) to my smart TV, and this worked without problems. Yesterday I noticed the video skipping more often and being more unresponsive than usual. This seems to indicate my local network being slow, but Speedtest.net also showed very slow speeds all of a sudden.

My set-up is this:
I've got my ISPs modem set to bridge. This is connected to my wifi router (ASUS RT-AC66U). This wifi router is in the same room as my desktop PC (about 4-5meters away). In my desktop PC, I have a TP-Link T6E 5Ghz PCIe wifi receiver, which is connected to my 5Ghz wifi network.

Now, my internet speed is 200Mbps down and 20Mbps up, however Speedtest.net measures it currently at around 15-20 down and 7 up. If I set my laptop at the same distance to my router, it measures very fast speeds. The same for my phone. Also, when I connect a network cable, my speeds are fast again. So it seems like there's a problem somewhere on my desktop PC or the wifi receiver.

What I already tried:
- Reboot ISP modem
- Reboot wifi router
- Upgrade firmware from wifi router
- Reinstalling TP-link wifi receiver in device manager
- Reinstalling TP-link wifi receiver with and older driver (Broadcom 802.11ac Network Adapter Driver 6.30.223.234)
- Checking recent Windows updates, but none were installed

I have no clue what is causing this problem. It worked fine a few days ago. Out of nowhere speeds on my desktop PC are very slow, while my laptop's speed is very fast.

What could be the problem here? Any suggestions?
 

dominionz

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Mar 20, 2009
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18,640
Looks like you diagnosed it pretty well. It looks to me that the adapter went bad since all other devices work fine. Get a new/another wifi adapter and see if it resolves the issue.
 

illuvattarr

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Dec 19, 2014
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4,510


Could a bad adapter make the speed slower? I would think if it's bad, it would just stop working completely.

Do you have a recommendation for a good model or brand of PCIe wifi adapter? Because I just bought this TP-link 1 year ago and this is not the first problem I've experienced with it.