Doing a full reset was a mistake, you should have followed the suggestions in the new router - installation instructions FAQ.

At this point, you’ve erased all data about your ‘old’ system, I’d suggest setting the up as a ‘new’ system, starting with wiring one of the Sonos devices to your router with an Ethernet cable, at least temporarily. Once the system has been set up, you may be able to remove that cable, depending on your setup. 

Why on earth did you reset anything? You should have set your new network to use the same SSID/password as the old one, and then no device would need to be changed. Too late now though.

Thanks for your replies. It actually wasn’t too late and as it turns out what I wanted to do. It was given to me in ‘the split’ by my ex partner, and I was needed to set it up for me with new details. 
I have managed to sort it using the Ethernet first, then disconnecting. All set up and working fine now.