You should be able to change the network if you temporarily connect a speaker by ethernet to your new router. Unfortunately, you need to connect over ethernet as your listed speakers lack BLE to change the network wirelessly with the new Sonos app, but this will avoid the need for a factory reset.

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

Set your new router to use the same SSID and password as your old router, then you will have to change nothing.

Maybe too late; but here’s the proper/easy way to change routers (without hassle) by the numbers...

1. Unplug your Sonos speakers 
2. Delete the Sonos app from your device
3. Setup your new router with same SSID and Password as your old router
4. Update your device (if one is available)
5. Plug-in Sonos speakers and let them come back (Status LED’s (if you have that feature enabled) should not be blinking. If you don’t have that feature enabled wait 15 minutes after plugging the last one in.
6. Connect your device to Wi-Fi of your new router *
7. Download and re-install the Sonos app
8. When prompted select “Join An Existing System”

 * It should auto-connect; or at least give you the option to connect to the same Wi-Fi SSID as was identified using your old router if you followed Step #3. Also, other Wi-Fi enabled devices should auto-connect or at least see the Wi-Fi SSID previously used and ask for same password 

Unfortunately Mr T even after connecting all hardwired one is still unable to change the network due to the new app! So have had to reset all and lost playlists etc..

Another own goal for Sonos….