Too late now, but you should have just set the new router with the same SSID/password as the old one, then nothing would have need to be changed.

Factory resetting your only device has made your problem worse.

If you tell us what router you have, someone might have a suggestion, else you’ll need to wait for overloaded Support to answer the phone.

I wouldn't know how to change the SSID to be honest. On top of that it's 4 months since I had the old router so the name and password are long gone. 

I slowly followed the instructions in the various help articles on the Sonos website and only did a factory reset when all else failed. Seems mad that Sonos would give erroneous or incomplete information.

The new router is an Sagemcom (CS 39000?) on the off chance someone has similar?!

Thanks.

As it is an older speaker, you might need to downgrade the Play:1 from S2 to S1, and control it with the Sonos S1 controller app.

Does this help?:

https://support.sonos.com/en-gb/article/downgrade-a-sonos-product-to-s1

Support really sounds like your best bet, there are technical things you could look at and try but all are more complicated than setting the SSID.

Listen to the hold system and see if Sonos is offering callbacks in your area.

Thanks for the replies. I might try downgrading to S1 as suggested by Rhonny. I should have a chance to try that tomorrow morning. Unless it's something particular to my router.

I'll report back....

Downgrading worked! Thanks for the suggestion Rhonny. 

I had to downgrade with the Ethernet cable. (Wirelessly, I fell at the same hurdle...entering the wifi password)

Once I downgraded using the Ethernet cable, I removed the cable and, using the S1 app, my Play 1 was detected.

Thanks again.