Are you not able to update the Network settings whilst wired to the new router as stated in the support page?

Your profile lists a Play:5 (Gen1) so using S1 app.

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

You could change the SSID/password for the new router to match what was previously being used.

If you have the same internet provider but just a new router then as MR. T says it is by far the easiest to just change your SSID (Wifi name) and password for your Wifi to the same as before, then all your devices should connect themselves.
Even with a new internet provider it should be the same procedure, and a new provider may have some blockages/different settings.

Also,with the old Sonos and new router be sure the router is sending out a wifi signal the Play 5 can decode, and security it supports.

https://support.sonos.com/en-us/article/supported-wifi-modes-and-security-standards-for-sonos-products

Thanks guys I’ve managed to sort it out . I deleted the app and re downloaded it , and it was gen 2 not 1 but thanks again for the support crossy72