@Naor Thank you for your detailed post. 

For Win11, please confirm you have tried the official driver for Win10 64 bits

Dirver : https://www.tp-link.com/support/download/tl-wn821n/

If adapter connected to Wifi but has no Internet, you could refer to the following instruction:
1. Confirm other devices could get Internet access from the same Wifi network 

2. Check if the PC get an IP address after connected to WiFi network, if PC has an IP address IPv4 gateway (router's IP), try to manually set  DNS to 8.8.8.8 and see if that helps. 

Step in FAQ here: https://www.tp-link.com/support/faq/41/

3. Disable other network adapter

4. Check if there is any access control, MAC filtering  or special settings on the main router;

If still the same issue, 1) can i have a photo of the IP address 2) Model of router 3) try to ping IPv4 default gateway and see share the ping result  https://www.tp-link.com/support/faq/841/
Thank you. 

Hello  @Naor 

Sorry for the late reply,  this could be due to some advanced settings on router, can you check if there is any Access Control, Blacklist, Parental control or any access rules for this network adapter?

Do you have other Wi-Fi network adapters on the computer, if so, disable it. 

Try a different channel & channel width for the wifi router, like Channel 6 for 2.4Ghz, 20Mhz, Channel 36 for 5Ghz, 40Mhz

You could try a different IPv4 address, like IP: 192.168.1.250; IPV4 gateway : 192.168.1.1;  Subnet: 255.225.225.0;  DNS 8.8.8.8

Please also check my private message for another driver to try. 

Can I know does this happen on both wifi bands 2.4Ghz and 5Ghz on the router?