I would expect that this is most likely some sort of wifi interference , with the family room not getting the data when streaming. In particular, I’d be looking at devices that may be too close, especially given your statement about the router being ‘right next to the PLAYBAR’.
Another possibility, although perhaps more remote, is simple duplicate IP addresses, which could easily be tested by a relatively simple network refresh. Unplug all Sonos devices from power, and then reboot your router. Once the router has had a couple of minutes to reboot, plug back in the Sonos devices. If this fixes the issue, it could only be a temporary fix, any router that has handed out bad IP addresses to the Sonos during the Sonos software update process might do so again in the future, so reading the router’s manual and learning how to assign reserved IP addresses for all of your network devices would be a good step.
Please don’t further factory reset any devices, ultimately, that deletes any data that might help Sonos help you, and as you’ve found, rarely ‘fixes’ an issue, at best sometimes postpones the reoccurrence.
This is just two potential causes for drop outs. Without hard data to look at, I’ve picked out the most likely to help answers, but should this behavior continue, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, 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.
