Keeps cutting out

Sorry but I think we’re going to have to agree to differ over Sonos’s reticence to readily admit to bugs in its apps. I went through the whole submitting reports (several in fact) process a few years ago and it was always something else until an upgrade and hey presto it was solved. I don’t think anybody would expect immediate upgrades but admitting there’s a possible problem would go a long way and stop any other nugatory investigation. My network is happily running everything else harmoniously, TVs (including NowTV), laptops, tablets, phones and a Niam Mu-so which works with no problem, even the Sonos app on the MacPro works fine (although there remains the slight annoyance that there isn’t the “play songs from this device” option) so I’m not sure how it can be anything else other than an iOS bug.
I remember the upgrade to Sonos 5 from 4 was a disaster for me--possibly around the same time as your problems.

I'd been on 4.x since I got my system. Held off on updating to 5 because everything was working flawlessly. Decided to upgrade when 5.1 was released in September 2014 and suddenly nothing worked. Followed all the usual trouble-shooting techniques, multiple network resets, WiFi noise reduction, channel changing, static IP addresses, etc. All no good; the system remained unstable for months.

I'd pretty much given up on Sonos altogether then I upgraded to 5.2 in December and suddenly everything worked like a charm again. It's worked flawlessly since--including following a move to a new home.

So yes, I'd say that there is room for a Sonos bug or two.