To stop the TV ‘group’ skipping the Spotify audio you should find that increasing the HT room ‘group audio delay’ to use a larger buffer size will solve the issue. See this link (item 5):

https://support.sonos.com/en-us/article/tv-audio-stops-or-skips

No help at medium or high - diagnostic 130775262

And this is whilst playing TV audio, as mentioned in your initial post? Maybe try just a general TV channel or something from a different App.

Spotify drop out - any info from log file?

Only Sonos Staff can read your Diagnostic Report - to get feedback from that you need to contact them direct via this link: https://support.sonos.com/s/contact

You mentioned earlier that it was your TV audio output - so is it the Spotify App on your TV or a connected device? Your post isn’t clear about where you’re playing the audio from - which Spotify App is it? 

If it’s not TV audio, but you’re perhaps using Spotify music from your mobile device then ensure your mobile is connected to the same WiFi access point as your main playback Sonos speaker and perhaps try using a fixed non-overlapping 2.4Ghz WiFi channel (eg: Ch 1, 6, or 11) with a 20Mhz channel-width, or if you are using SonosNet instead, then ensure it’s channel in the Sonos App is set to a completely different channel than the one chosen for the local WiFi signal.

You may find this support document perhaps helpful too:

WiFi Interference

LOL that link is how I got here…

Using Sonos app to stream Spotify.  So I have to do chat or live call to have someone look at these log files?  Drag that we can’t see them directly, and have online self-service access to see what they indicate...

Either chat or a phone call gets you to a person who can access those diagnostics, I.e. a Sonos employee. My recommendation is a phone call…but you can save a chat, where it’s much harder to ‘save’ a phone call. 

Have you tried the things mentioned in the Sonos Support WiFi interference document, such as changing your router wireless channels and band channel-width etc? I would maybe try that and perhaps just see if it may save you a phone call - the Staff might go onto just suggest trying those things anyway (perhaps?), aswell as rebooting your products.

> Have you tried the things mentioned in the Sonos Support WiFi interference document, such as changing your router wireless channels and band channel-width etc? 

It’s a Linksys mesh setup; the channels are ‘auto’ - not sure how I can display what is selected, the iOS app runs a channel detect and selects the ‘best’ channel.  

Guess I’ll try for a live chat sometime to get some info from the diagnostic logs.