If by “reset my devices” you mean factory reset, you’ve wiped all data from the speakers, so you need to treat them as new devices and install them from scratch. If your app is still remembering your old network, try “manage networks”, or else start by deleting the app and reinstalling it. 

Hi,

Thanks for replying.

Yes I had to factory reset all my devices (I don’t think you can change network on Play 1 and Play 3s), and re-added them one by one using the Sonos App on my tablet. That was yesterday. Now today, they still show in my App on my tablet, but I can’t connect to any of them. I reinstalled the app, and joined my Sonos network, (it doesn’t give my a choice of networks to join - just the one it ‘sees’ on my wi-fi). When it connects to that (which it happily does), I get the list of my devices, but can’t connect to any of them.

The easiest way to have things connect when changing to a new router is to configure  new router with the same SSID and password as the old one. But since you have already reset the speakers, which should be the last resort, you should proceed with setting your speakers up as new. 
With your tablet, remove any remnants of the old networks. If you can do a network reset, that’s what I would recommend. Then rejoin your system.

Well that's just plain weird. I've done nothing. But whilst posting this question, the Sonos app and network seem to have sorted themselves out. My tablet is now showing my renamed network, and all my devices correctly, and I can connect to them. 

It just seems like it's taken a while to propogate the 'correct' network and reset devices around all devices/apps.

Glad it’s sorted; enjoy!