In recent months I'm noticing short audio dropouts in any/all of my 18 Sonos units. I searched the forum on "dropouts", but most seem to be related to specific music sources. This is mainly apparent with speech vs music sources. I have two Play:5's (1st gen) which use the Line In to introduce TV audio into the system. It's not these inputs that is the problem. i.e., if the program is playing in the room I'm in and in an adjacent room, if the audio drops in my room, I still hear it playing in the next room. This problem seems to occur mainly on these 2 TV inputs. However, that may be because dropouts in music aren't as apparent, and/or a lot of my Sonos time, when I'm paying the most attention, is with TV audio.
Another more recent problem is Sonos units dropping off Groupings. I'll have 3 rooms in a Group and find that there is no audio in one zone. If I check the iPhone Sonos app, I see that it is no longer in the Group. This can happen every few minutes. The physical system hasn't changed in a long time. Only Sonos software updates. Since it has total control over the system, it's also possible that the problem could be with the iPhone app.
Any ideas where to look? Sonos customer service has tanked with "over an hour wait time", perhaps coincident with taking on the Alexa program. I would be happy if we were able to revert back to earlier software versions that worked. With 18 Sonos units, I'm too heavily invested to consider an alternative.