More than likely a local issue with wifi interference , rather than something with Sonos itself, otherwise there would be hundreds of thousands of posts.
I’d suggest your first step, onerous as it may be, given the size of your system, is a fairly simple network refresh. Unplug all of your Sonos devices from power, then reboot your router. Wait two minutes, then plug in your Sonos devices to the power again. Wait another two minutes, then test.
If, as I suspect, it fixes your issues, I’d look in to a couple of things. First, I’d reboot the router more frequently, and it might help us to know what type/kind it is. Second, I’d consider setting up reserved IP addresses for all of your devices in the router’s DHCP table. If you can. Since we have no idea what router you have, it’s hard to be certain. I don’t have that capability on my T-Mobile device, but then it reboots itself due to power loss fairly often on the island I live on.
Alternately, you could submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.
