I would  be awfully tempted, first, to unplug everything from power including the router, and plug them back in, one at a time, starting with the router first, moving your way through the Sonos, and ending up with the Sub last  

It is also possible the wireless circuits in the Sub has failed in some manner. If the above fails, while you have it wired directly, submit a system diagnostic, and contact Sonos directly. 

My approach would be to reboot the bar, then if necessary, SUB. I’ve also had some odd issues that required force closing or re-installing my iPad SONOS controller.

In my opinion it is risky to reboot only the router. It is possible that you could do this 100 times in a row, get lucky, and there will be no problems. But, on reboot 101 the phantom strikes and there are multiple intermittent issues. The incorrect assumption would be that “something broke” or the last device updated is at fault. Reserving IP addresses in the router will minimize this risk. Notice that I said “minimize”.

In my opinion, as suggested in the above post, if you elect to reboot the router, one should power down everything, then reboot the router.

Long ago I had multiple network issues and had to reboot my network once a month or so. Otherwise the phantom would strike. Everyone who used that router for anything beyond a simple network with a couple computers had similar complaints. The night that I trashed that router my issues stopped. At this point I don’t reboot the router from one year to the next. If any reboots are constructive, they occur naturally when the power grid goes down.

Which model router are you using?

I suggest that you refrain from Factory Reset of the SONOS components without further consult.