I had problem with my Sonos app losing connection with all speakers every few days. Had to go through the reconnection including switching off router multiple times to find them again. I have a playbar , subwoofer, play 3 and play 1.  I had a Google mesh with Virgin router in modem mode but changed to TP-Link Deco 6e thinking it would improve but it got worse.

i tried all solutions on the forum, turned off guest network, turned off 5g , wired playbar direct to the primary router and spent 2.5 hours on the phone with support. These led only to brief connections. 
I then moved my primary Deco6e router 4 metres away  from the playbar and have now had no lost connections for 4 weeks. I would suggest trying this simple solution before the other more technical answers. Seems that interference was the main issue.