Check out 1.3.7 Beta. Up to 1.2.1 the wifi worked fine, then only in Beta. I lost link to 1.3.7, you have to search on forum. I had much bigger problems with wifi at 5ghz

@noseran I don't know what could be wrong, did you turn off the firewall ..? https://static.tp-link.com/2020/202001/20200123/Archer%20C6(EU)_V2_020110.zip

@noseran Where I read, they recommend the switch, if it does not work now, try it. I always went back to 1.2.1. I doubt they will make a mesh switch. I wrote a few months ago with a senior engineer...

Factory Reset? Online update via router options? If everything works, it might be better not to update, sometimes there are more problems than the benefits of newer software.

@noseran I did a factory reset 2 times after checking the new firmware, it's something new for me, but it worked. Tell me better where is the OneMesh disable option? Have you used an extra switch...

At the moment, Wifi 5ghz works OK, let the final software work the same. As for ping. Too short to judge general behavior.