There should be zero relationship between the TV being on/off and your ability to connect to the system via the iPhone app….unless your TV is also the router for your internet LAN.

Can you describe your network in more detail? What kind of router do you have? What channel and frequency is it using? Is the Arc wired, or connected to a wireless signal? Are your system up to date with both the latest controller, and the latest firmware on your Arc? 

i have an asus RT-AX88U and sonos is connected to wireless 2.4ghz.  yes, both are on the latest firmware.  i just tried rebooting everything and it can’t connect still.  weird.

Try disabling Airtime Fairness for both 2.4 and 5GHz bands in the router’s settings.

There are a couple of fairly extensive threads about ASUS routers and the issues associated with them. Let me see if I can dig one up.

Conversely, you could call Sonos Support directly to discuss it.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

 comes to mind, as does

I believe there are others scattered around, too. 

looks like that was the issue.  i can connect now.   odd that it’s affecting it now...i’ve had sonos for over 6 months and this is the first time i’ve had this issue.  either..thx all!!!

thx!!!  appreciate your help!