@lmaoleonix 

Hi, welcome to the community.

Online Gaming, especially multiplayer games has a high demand on network latency and an Ethernet connection would be a better choice than Wi-Fi.

Did your computer have its own built-in wireless adapter? or have you ever considered a higher standard, like a Wifi 6 network adapter?

At the same time, you could refer to the following suggestions to see whether it could improve the network lag a little bit:

1. put the antenna of T3U plus directly towards Archer C80 and put them in a proper distance, 3-5 meters would be great.

2. change the 5Ghz wireless channel of C80 to channel 48 and channel width 80mhz.

3. manually install the following driver for T3U plus

https://community.tp-link.com/en/home/forum/topic/509006

Thank you very much.

Best regards.