The IP issue is easy, go to your router’s DHCP page and assign all your Sonos devices a static/reserved IP. Power down all Sonos, reboot router, power up your Sonos.
I’d do that before looking into the RF problems possibility.
Take a look around your Sub and whatever you have it hooked to for other 5 GHz devices. Try to give them 3 feet of distance from each other. Sometimes even a few inches more will help if getting the 3 feet is tough so try that.
You can wait for the disconnect / connect to happen again (if it still does) and submit a diagnostic to Sonos and then contact them with the number to have them look at the internal data.