In order to make this more generic I've added these rules to my AdGuard Home custom filters # Tapo Camera...

@Celico I just mapped the broken relay URLs to use1-relay-dcipc.i.tplinknbu.com and it works fine....

@Weavey Both my cameras started requesting non existent URLs again every six seconds. If you have the capability, do a DNS rewrite of the bad URLs to this domain : use1-relay-dcipc.i.tplinknbu.com

Still getting multiple router connect messages with the latest firmware

@lukass2000 From my reading of the articals it can create loops all in on its own even without a WiFi connection. It's to do with how it uses the STP and multicast when it's looking for compatible...

@lukass2000 Simple enoght to test, disconnect the Sonos and see if you still get loops. From a brief read it looks like issues with versions of the STP and multicast traffic. Also, do you have WiFi...