Are you able to use the same SSID (network name) and password as your old network?

Yes, I could go in a change the SSID password to that of the old WiFi network. But I haven’t yet canceled my Comcast service, so if I fired up that gateway there’d be two WiFi networks with the same SSID and password.

Can you not just unplug the old router and change the SSID and password on the new router?

I just having the same issue, the Network Management tool is completely broken and ineffective. The only solution I have found to be semi-successful is to remove all trusted networks from the app and then factory reset every Sonos item and add them all again as a new system.

You will also need to remove your old Wifi networks from your phone so that it can only connect to the new network that you are setting you system up on. If you dont do this it causes even more issues.

Doing this has allowed me to set everything up and all the speakers do show up in the app. However since doing this my app frequently goes crazy and loses connection with random speakers and says they cant be found only for them to appear 10 min later.

Fantastic hardware and speakers but ASTONISHINGLY bad software and support for a global product and this price point.

Your steps do not seem necessary unless something is really wrong - since you have network related problems I’d look at the router.