Don’t do any factory resets, please.

Try unplugging it, and any other Sonos devices from power. While they are unplugged, reboot your router. Once the router comes back up, plug back in all Sonos devices.

It’s also worth checking the wifi interference FAQ, paying particular attention regarding interference from outside your network. 

But if neither work, I would recommend that you submit a system diagnostic , and call Sonos Support to discuss it, or post the diagnostic number here for a Community Moderator to pick up. If the Arc is your only Sonos device, you may not have the opportunity to submit that diagnostic, in which case I would call in. 

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, there are more options available beyond just the diagnostic analysis. For instance, when they are talking to you on the phone, they may want to ‘remote’ into your system, something that can’t be done when on chat or responding on these forums. 

Thank you. It's at the point where I need to call them. I've rebooted router and unplugged boost with no success. I have 3 One SLs, boost, Arc and sub. Only have this issue with the Arc.

Your symptoms  of working after a few days does smell like a duplicate IP address. 

in addition to what Bruce says about powering off your router you need to power off every single device that connects to your router, wired and wireless.

Only then power on the router, waiting for it to be fully running before turning on any Sonos devices.

Assuming you re now running again look at your router and work out how to reserve IP address for your Sonos devices.