Audio glitches live, but ok after skipping back

I've been using an Apple TV 4k for 2 weeks, having given up on waiting for fireTV 4k fixes. Using Channels DVR on a powerful Linux server, and wifi network is fine (50Mbps). Unfortunately I'm finding that when a channel first plays it very often will have tiny glitches in the sound, almost like a static click. These will normally be randomly, e.g., a few over the first 5-10 seconds. Every time, if I then skip backwards and re-play the last few seconds of the channel, then everything is perfect. So that suggests that the data coming from the HDHomeRun is fine.

Also, if after changing to a new channel I press pause for a second, and then continue to play back, the glitches do not occur. So it seems to only be from playing in real-time.

I am in the UK, and this happens on SD channels very badly, but also on HD channels, but less obvious (smaller duration glitch).

Any ideas?

Can you submit diagnostics after playback and post here when they've uploaded