Entire system keeps disconnecting

That sounds like a network issue. Please describe your network such as hardware (yours or that provided by ISP) and any changes or additions make. Changes made does not include adding new Sonos products.

Using Netgear MR70 mesh router with 2 satellites.  Have not made recent changes to router settings, other than removing my guest network as suggested by a Sonos support system.  I did remove an Ethernet-connected Playbar when I added the Arc Ultra, the Ultra is not ethernet-connected.

OK.. is your main Netgear router connected to hardware provided by your ISP that houses both a modem and router (combo box)? Also are the WiFi bands separated by different SSID’s?

Main router is connected to Spectrum’s PC 15 modem.  I do have 2 separate SSID’s for 2.4 and 5ghz, but I am connected to the main SSID (I may be mistaken but I think the main SSID includes both bands).

OK…

I suggest you unplug all Sonos. Do not factory reset your Sonos.

There is no such thing as a main SSID. Therefore, open your routers admin and make sure ALL Wi-Fi bands have the same SSID. 

While in your routers admin disable band steering which allows the router to dictate what WiFi product connects to a particular band. Also, make sure Airtime Fairness is disabled.

Reboot the router and let it comeback

Delete the Sonos app from your device and reboot it

Plugin your Sonos and let them comeback 

Reinstall the Sonos app and select “Join an Existing System, follow prompts and sign in with  your credentials 

Thank you.  I’ll be trying this in a few hours and report back.  

👍

Just a clarification about Main SSID. You may have a Guest Network with a different SSID which may have prompted your use of the term Main SSID. Since Sonos doesn’t operate on a guest network the term Main SSID doesn’t apply.

 Do you see the Spectrum WiFi?  If so put the PC 15 into “Bridge Mode”.

By all accounts and my research the Spectrum PC 15 is just a modem. Therefore there is no WiFi signal being broadcast.