You can plug them all into Ethernet and control with the mobile app.

https://support.sonos.com/en-us/article/recommended-settings-for-using-sonos-with-ethernet-networks

You could also use the PC or Mac app (for most things) from a wireless or wired computer to see if that helps.

You might want to work on the underlying problem that is making your system unstable too. A couple suggestions that have helped other folks.

-- Set static/reserved IP addresses for your Sonos devices using your router’s DHCP page. It is usually a quick and simple task, just a few clicks. Then power down all Sonos, reboot the router and power the Sonos back up.

-- Check for wireless interference, there is an excellent FAQ on that. In my case I found an external hard drive that was spewing RF noise and taking out one of my speakers, In the other I had two different sets of speakers too close together (inches apart) even though one set were in different rooms. Moving then a couple feet apart (3 would have been better) and my system has stopped fighting me.

https://support.sonos.com/en-us/article/reduce-wireless-interference

Thanks for the link.

The devices are several feet plus apart.

I will try the static address

It’s possible that the Gateway installer changed the password and didn’t give you a copy.

Maybe you could get an ISP support person to change or disclose the password. Another approach is to factory reset the Gateway. There is some risk here because this will default all of the Gateway settings -- including some that you may not aware of.

I just set static and will see if that works.