I have a Wifi 6 Asus Router and my Rokus seem to work fine with whatever changes I made to Wifi, I found no issues using WPA2 or WPA2/3. Things would start to fall apart when I added 2nd Asus Router with AiMesh, and not immediately either. I could be using Rokus for a few hours, then they all flake out at the same time, but yet other network devices continue to work. Today I changed 5ghz channel bandwidth to 80mhz only. Made sure unchecked 160MHz, manually set a control channel to something above 150 (153).
Has been stable for a while now with these changes.