If you’re continuing to have issues with the App and/or your Sonos devices and can easily reproduce them, but perhaps haven’t yet contacted Sonos Support, then maybe just give them a call.
Here is the link to contact them…
https://support.sonos.com/s/contact
Their App and speakers seem to be working okay here, but I guess different setups, hardware and Home networks can vary. It sounds to me like you may have an mDNS/SSDP multicast issue, perhaps, coupled with wireless interference, but maybe see what the support staff can discover during your call.
