Best answer by Airgetlam
Second, and to be honest, I'd do this at the same time, unplug all of your Sonos devices from power before you reboot the router. Once the router is back up, plug in your Sonos devices one at a time, starting with your BRIDGE. Give each one a minute or two to boot up before moving to the next. There's a fairly slight chance that you've got some duplicate IP address issues going on, but that's a minor chance. Doing it certainly wouldn't hurt anything, though, so it's worth a shot.
If neither of those work, I'd recommend that you submit a system diagnostic within 10 minutes of replicating this issue, and contact Sonos to discuss it. There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.