Hello,

So problems with my wi-fi adapter started like over half year ago after some windows update, and since then the usuability keep chaning drasticly. So most time i can't connect to my 5ghz network:
Chanel 48 - tested also on 40, 36
Tested on 20, 40 and 80mhz
Different SSID names for 2,4ghz and 5ghz network
Firewall on router unlocked
Signal strenght: 35-50% (usualy from 70 to 55 dbm)
Same on USB 3.0 and 2.0
 

2,4 ghz working without any trouble, always connect, no drops
Windows versioin:  10.0.19041 Kompilacja 19041
Driver version: 5.1.34.0 | 16.11.2017


All my other devices connect normally, so it shouldn't be ISP problem. I've tested my T2U on other devices and sometimes on other it will connect, it won't connect at all or sometimes even on my main PC it will duplicate my SSID, so i get like XXXXX_5ghz and XXXXX_5ghz 2 and will work on like 5 mb/s and will get unprotected connection (so it duplicate SSID and make it without any WPA security - router only see one SSID).
I've downloaded newest drivers for T2U v2 from tp-link page, i got new chipset drivers and when i did it first time, or when i even reinstalled same driver (so unistall driver or even click on same driver for TP-link adapter in Device Manager) the adapter would connect to my 5ghz network. Lately its working diffrently - once it will connect to my 5ghz network trought TP-Link utility (I have read on forum that it could help in connecting to 5ghz and few times it helped) with no problems, sometimes it will connect after like 5-10 attempts and sometimes it won't connect at all. I can be connected to 5ghz, restart my PC and then i won't be able to connect to 5ghz again. Also while i finally will be able to connect to my 5ghz, and it will work perfectly fine, no ping drops, full speed, good connection, the adapter will turn off itself for like 1-2 seconds and i drop connection. After this sometimes i'm able to connect again to my 5ghz and sometimes i won't be able to connect to 5ghz again. Turn offs are kinda random, usualy after like 1-3 hours of working, usualy before adapter turn off it will like drop signal strenght drasticly, kinda freez, and then turn off itself and on again.
Edit: when the adapter turn off the WLAN Report show:

The WLAN AutoConfig service detected an open. Recovery will be attempted. 

Recovery Type: 4
Error code: 0x0
Cause of trip: 2
IP address family: 0

In next report:

Cause: The network was disconnected by the driver.

Also sometimes it won't see any 5ghz networks and after few seconds it will just get back to normal. 

Also got WLAN reports but they are in polish so if needed i can try to translate them into english.

Also one thing i've noticed. I'm using inSSIDer and when i'm watching the signal of the networks it is in constant spike, like it change every tick from like 70 to 60 dbm and it keep repeating, but while i connect to the network it will be stable and the line will be flat and connection strenght usualy will get better:




Things i've tried:
- new drivers
- old drivers
- chipset drivers

- TP-Link utility
- forgetting/deleting network and connecting to it/adding network before connecting and then connect

- changing chanels, other devices, connecting to other 5ghz network, changing mhz, changing USB ports