I was unable to add or set-up devices in Google Home on my Galaxy Fold 3 despite AP isolation being diabled and UPnP being enabled. After updating the router firmware, the UPnp issue/message went away but the AP isolation was still an issue. I was considering setting up my old router on a separate network, but that solution didn't make sense. My son then asked me if I tried using the Google Home app on an iPhone. I tried it and I was able to add/update/set-up my Nest Hub and JBL Link Music speaker. Could it be an issue with One UI? I haven't verified the issue with a Pixel phone yet. My son has a pair of Nest speakers that need network updating. Will keep you posted.