ARC disconnects from SUB and Surrounds when TV is turned on

What router are you using? Try unplugging all the speakers from power for a couple of minutes and rebooting your router.

Are you able to wire just the Arc to the router with an ethernet cable?

Right now I’m using a ARRIS cable modem, but I've also tried a Linksys mesh and just an old Linksys, same problem with all three, so it’s not a router issue.  Tried rebooting  components with different routers and same problem.  My original plan was all wireless and it worked for a month, now it only works if a components are wired.  Wiring just the ARC didn’t fix the problem.

You could still be experiencing wireless interference:
https://support.sonos.com/s/article/3286?language=en_US
 

If you remove the Sub and surrounds from the Arc in the Sonos app and re-add them, does it make any difference?

Do you have any other Sonos speakers wired to your router?
 

Run a diagnostic within 10 minutes of the Sub and surrounds disconnecting and report the confirmation number here so Sonos staff can take a look at it.
https://support.sonos.com/s/article/141?language=en_US

Note that the SUB and surrounds connect to the Sonos Arc using a 5Ghz channel created by the Arc itself. If turning on the TV is creating enough interference to that 5Ghz signal, the devices will disconnect. Note that it’s possible that it’s a process of turning it on, rather than a constant level of interference. 

Those devices do not connect to your router directly, but get proxied from the router through the Arc. 

It might be worth checking to see if there’s a firmware update to your TV to address that potential issue. In general, the four inches between the bottom of the TV and the Arc should be enough, there’s certainly an aspect of the FCC checks designed for external RF interference rejection in every electronic device. It’s not infinite, though... 

And frankly, I’d really be tempted, then next time it happens, to submit a diagnostic, and contact Sonos directly to see what the logs say. 

I’ve tried moving the ARC a couple feet from the TV to see if it’s RF interference, still has problems.  I have already tried disconnecting the HDMI from the ARC and turning the TV on.  It disconnects when the HDMI is plugged in not when the TV is turned on.  It also disconnects when I plug it into the optical adapter connected to the TV or a BD Player.  So it’s the starting of an audio stream that appears to cause the problem not powering up a TV.

I’ve tried reseting everything and reinstalling the system, no effect.

I plan to run a diagnostic tonight and send the results to Sonos, but their chat bot was no help.  They do have a phone number but I really need to get this fixed by text, email, chat or this site.

I understand that the Sub and Surrounds use a proxy through the ARC on a dedicated 5GHx network.  Before retiring I design embedded firmware and RF communications systems.  I tried running all components through my wifi instead of the Sonos network, had the same problem.  I have noticed that when the ARC disconnects from the Sub and Surrounds they also drop off the network both when it’s using a Sonos 5GHz network with the ARC as a proxy and when all components are connected through my wifi.  

I’m wondering if it could have something to due with regional restrictions.  I’m in Puerto Rico.

Can you perhaps post two screenshots of your Sonos App’s ‘Settings/System’ list showing your devices when they are all working together nicely ..and another to show what happens to them when the surrounds drop and stop working… thanks.👍 Can you also kindly confirm that you have not switched off the wifi/wireless adapters on any of your HT devices.

I realized the problem went away when the TV was unplugged and I had the Sonos ARC connected to the BD Player. So I turned off the TV’s wifi and wired it to the router.  Problem appears to be fixed, everything is working.  I tried moving the ARC a couple feet from the TV and still had problems, so this TV really has a bad interference problem that popped up on the last firmware update.  So all you LG CX owners beware you might need to turn off the TV’s wifi and wire into the router.  

Crap the problem is back, SONOS has a really poor ability to handle RF interference that makes wireless operation impossible in a condo.  I’m in a condo and I think I’m getting interference from the other wifi networks in the building.  So I’m going to use all the SONOS components in wired mode and use TP wifi routers in client mode to carry the audio streams.  

I’m surprised 

That's not making much sense to me as I understood it was the ‘surrounds’ and ‘Sub’ that were ‘dropping’ from your Arc. Those connections use the 5Ghz band and that’s not normally a crowded band, even in a condo environment, not least that radio band would normally not travel far through neighbouring walls, unlike the 2.4Ghz band - I suspect there is perhaps something else amiss here if it is your HT surrounds that are disappearing and losing their ‘bonding’ over what is an ad-hoc connection to the main HT player and not a connection to the local WiFi router.

Forgive me for asking this ‘perhaps silly’ question @mchorn64, but are you certain that the two surrounds and Sub are ‘bonded’ to your Arc and not ‘Grouped’ with it? Only a ‘grouped’ setup here, would actually explain why the other speakers always dropout, when you power on the TV.