My Sonos Beam and LG C2 hate each other

[beanheadmcginty]

Every couple of days or so, my Sonos Beam sound bar and my LG C2 telly have a falling out and suddenly - in the middle of a programme/film - decide to disconnect from each other and the TV reverts to its own speakers. Nothing will solve this problem except unplugging them both repeatedly until they forget they knew each other and then they link up fine. During the period of acrimony, the Sonos app on my phone says there's something else plugged into the TV that's interfering (there isn't) and the TV acknowledges the Sonos is connected by name, but refuses to send signals to it.
What the hell is going on? I bought these two bits of kit as I was told they were the best of their kind, so why can't they just fucking work?
Should I connect using something other than ARC?

[falafel]

Optical works OK for me (my TV is actually a second hand commercial display with no speakers and no ARC) and the Beam is set up to receive the signals from my LG remote so it's almost, almost like ARC. But you would lose the power on/off capability I suppose (does the Beam use that? I think not).

Still, it should be a plan B and I have no idea how to address the specific issue you're having. But just be aware that you can fall back on that.