Sounds like you have some network issues, that is definitely not the way the system is supposed to respond.
The first step I would take is a simple refresh of the network, by unplugging all Sonos devices from power. While they are powered down, reboot your router. Once the router comes back up, plug back in the Sonos devices and see if this behaviour continues. If it does not, you may want to look into reserving IP addresses for all your network devices in your router, instructions would be in your routers manual.
While I suspect that process will resolve the issue, there is a small chance that it may not. If not, after the system locks up and you reset it, submit a system diagnostic within 10 minutes of the reset, and call Sonos Support to discuss it.
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 phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.