https://support.sonos.com/en-gb/article/connect-sonos-to-a-new-router-or-wi-fi-network

Are you putting the phone and Sonos on the main WiFi and not the guest WiFi?

I think the Verizon router has a connected devices limit, you might check that.

I have also been trying to set up my Sonos with a new Verizon 5G Home internet system.  I can get it to work but it is not stable. I have everything connected with ethernet except for two Move speakers. I have disabled WiFi on the wired ethernet devices.

One issue is that It looks like the iPhone Sonos app is sensitive to a week wifi signal and will loose the system because of that.  I am considering getting a signal extender for the Verizon router but hate to invest that money if that does not solve the problem.

Thanks for the note. Glad to hear that I'm not the only one experiencing this. I have a Deco mesh wifi system, which is awesome, but the connectivity issue remains. So don't spend the extra money.

I can't connect using an ethernet, as it's not practical.  And the whole point of both Sonos & Verizon was the lack of wires!

I'm going to write Sonos to, hopefully, address the issue.

CHEERS!