Maybe try these steps…

1. Navigate to https://internet.xfinity.com/
2. Sign in with your Xfinity xFi account
3. Once logged in, click the Devices or Connect tab, then click on the Paused Sonos device
4. On the following page, click on the Unpaused Device button
5. Click on Apply Changes to complete the unblocking process of the device
6. Repeat for each Paused Sonos device
7. Once completed, the Sonos Player(s) will be able to connect, register, update, or stream. You may need to reboot the affected Sonos component(s)

While replacing a router, everything on the network should be shut down. On restart the units will start using the new router. It will be less work if the new wireless uses the same SSID (WiFi name) and password. At this time you should “reserve” or “fix” IP addresses for all regular network clients. This is especially important for SONOS units.

As someone who had to use Xfinity for much of 2022, you have my sympathy.