@Sledger17 Is it EU? If it is EU version, it only supports band 1 for the 5GHz, which is designed to comply with that of CE regulation. While it seems that the Xioami Mi10t 5G is broadcasting on band...

@DaZzleFM Hi Darren, have you checked this official one? You may update to this version, then monitor the connection: https://www.tp-link.com/support/download/archer-vr400/v2/#Firmware

@icekoala May I know what is the current Windows 10 version of the computer, 1909, or 2004? You may verify it as below: https://www.tp-link.com/support/faq/2722/ What is the model number of your home...

@MarianoC Try to reset the C7 to factory defaults, leave the A50 and A51 disconnect from the 5G network, then monitor the stability. If this always works fine, ensure there is no special settings on...

@KingRabbid Are the devices still able to see the 2.4G network when they disconnect from it? Please try to upgrade the router firmware we provided on this thread, then monitor.

@Dani_Bischoff Will discuss this on your own post: https://community.tp-link.com/en/home/forum/topic/252676