Got a new router tp link archer AX55.
Since I set it up, all yeelights stopped working. It kept timing out.
I did as suggested.
-turned off 5ghz
-change DNS to 8.8.8.8 and 8.8.4.4
-simple SSID
None of it worked
BUT …
it finally worked when I changed the “Security”
from WPA2/WPA3-Personal
to WPA/WPA2-Personal.
I slowly changed the DNS and 5ghz band back, and all working now.
Maybe this might help someone