Usually rebooting either from an update or power loss/restore.

Or possibly a heat related issue? You can read the LED states FAQ, which I think covers the Arc Ultra, too. 

I had not long done the latest app update before hand, hard to tell if It was a short power cut, as I had nothing on at the time as it was late.

Thanks chaps, will see how it goes, so far it’s been ok since.

Noticed this with our Arc Ultra and Sub 3 setup as well.  It happens any time the system is idle for 5 minutes after use.  Fairly confident that this did not happen with our gen 1 Arc.

If you power cycle the sub you’ll notice the blink pattern differs from this idle pattern - I suspect that this isn’t a reboot but rather a change in the wifi state on idle.  Interesting that it didn’t happen with the original Arc but it does seem to be intentional rather than a random power drop or overheating situation as it’s reproduceable and consistent.

I thought about giving support a call to verify this but figured I’d get a tier one tech who didn’t know what I was talking about.  @ledzep1 are you able to reproduce the behavior on your end (play a song, halt play back, wait five minutes)?

@blunderdome

Hi

Not noticed the light flash since, I will try what you said, but do you mean play a song from the Sonos app,  pause the song and wait 5 minutes?

Yeah, that should do it.  Or watch TV and then turn the TV off.

Arc Ultra is making an idle mode scan to look for the best 5GHz channel for the satellites. For some reason this causes a temporary disconnection, triggering the LED flash as the satellite reconnects. On previous soundbars it didn’t. 

That makes sense!  Curious as to why a scan would necessitate a disconnect.  @Corry P is this a bug that we should be reporting or intentional?

Hi @ledzep1 

Thanks for your post!

I am glad to hear this only happened after you stopped watching your content - please let me know if this ever results in a loss of audio from the Sub, as it sounds like it would if it happened during playback.

It does sound like the Sub was performing an OS restart, which is slightly quicker than hard boot from power-off. It is usually seen when a system swaps from being on SonosNet to Station mode, or vice versa, and also when an ethernet cable is attached or disconnected (which is very nearly the same thing).

If you see it happen again, please submit a support diagnostic (after the flashing stops) and let me know here that you have done so, and I’ll take a look for you

I hope this helps.

Hi @blunderdome 

Good question - we have not received training/warning that it should be happening. I’ll see what I can find out.

Funny, had the exact same experience a few days ago. Turned off my TV and a few minutes later I notice my Sub Gen2 was flashing white, I don't know how long it has been flashing but it was flashing for about 15 seconds after I noticed it.

Haven't experienced it before or since, haven't checked either.
Only thing I've noticed is Ulta has jumped from 5Ghz to 2.4Ghz even though my router is close and the signal is perfect. (Have a Wifi 6 router)

Hi ​@Peter_254 and ​@ledzep1 

I have now noticed this same behaviour, and I think the above information is key - a few minutes after audio stops, satellite speakers will go into an energy-saving mode whereby they will move to 2.4GHz until receiving an instruction to move back. I believe this is what is happening as you see the white, flashing light, and as a result, it should not be anything to be concerned about. It does seem to be new behaviour introduced with Arc Ultra, but I don’t know if is intentional and here to stay, or not.

I hope this helps.

Thanks for the info, not visited the forums for a while, just noticed another guy with same above and you as well. Can't say I’ve noticed it happen again, thats not to say it hasn't done It though, as I would only notice it in complete darkness and my sub is tucked away out of sight.

Happy Christmas to all.