[SOLVED] Only PCs can't connect to 5GHz Wi-Fi - Windows 10 AC600

[Maxiu1337]

Current device: Asus X756UX-T4244T
Wi-Fi adapter: FRITZ! AC430 and TP-LINK Archer T2U AC600
Router: Unitymedia Connect Box
( All drivers updated )
Hey,
after seeing how big the speed difference between my 2.4GHz and 5GHz is I tried connecting every device with 5GHz. My iPad and S9 connect with 5GHz instantly without any problems. When I try to connect with any PC after about 5 seconds of loading my Wi-Fi adapter (AC 430) disconnects, then after like 3 seconds the adapter reconnects and it says "cannot connect to this network". Exact same thing with the other adapter and with other PCs.
Connecting to 2,4GHz is working 100% fine. When I use the same SSID for 2.4G and 5G it automatically connects to 2.4G even tho I have 5G as preferred in Windows.
I've really tried everything I could find already: Tried 2 different Wi-Fi adapters, they ALL support 5GHz and 802.11ac - Tried 3 different PCs (all Windows 10), reset my network settings, drivers, password is 100% correct, restarted router multiple times, tried all USB ports, changed SSID so 2.4G and 5G are not the same anymore, tried every channel < 50 and all Wi-Fi standards, checked all settings for the adapters + windows, disabled firewall, enabled high-performance mode on my notebook, unplugged everything....

This is very very weird because all my devices except PCs connect to 5GHz. When connecting with a PC the Wi-Fi adapter resets during the process and it fails to connect. It feels like they are being blocked by something. Since my 3 PCs don't connect and the process looks exactly the same (Adapters reset/disconnect while trying to connect) I'm sure it's not a software issue. The adapters are also brand new so they're not the problem. What's the difference between a mobile/iPad Wi-Fi card/adapter and a PC Wi-Fi card/adapter? Why can my mobile devices all connect to 5GHz but my PCs can't? Has anyone ever fixed or experienced this? What else could I try? Should I contact my cable internet provider if it's related to the router?

Thanks in advance

 

[Remeca]

What kind of range are you trying to get? 2.4 has much better range, especially through walls. Try putting a pc in the same room and connecting. If one of your PC's is in the same room already, and it still doesn't work, then it seems it may be an issue with the router. Maybe try resetting it to default settings and trying to connect without changing any default settings.

 

[Maxiu1337]

What kind of range are you trying to get? 2.4 has much better range, especially through walls. Try putting a pc in the same room and connecting. If one of your PC's is in the same room already, and it still doesn't work, then it seems it may be an issue with the router. Maybe try resetting it to default settings and trying to connect without changing any default settings.

I even tried it while standing next to the router and in general, the PC(s) is just a few meters away from the router. I got the router and Internet set up a few days ago since I moved so resetting it wouldn't do much since it's brand new but I'll try.

 

[Remeca]

Did you try connecting to 5ghz with the 2.4 GHz network disabled?