Getting an new router does not mean you need to keep the new SSID and password for your wifi. I’d advise you to change the SSID and password of the new router to the SSID and password of the old one. This way your devices might not even notice there’s been a router change. You need to get rid of the old router after you’ve done this.

By the way stating you’ve “tried everything” you do not help the people willing to help you. If you explain what steps you have taken, it might also prevent people taking the time to answer you - just for things you’ve already done. If you’re not willing to use my advice, please state where you’re tripping up in the steps stated here: https://support.sonos.com/nl-nl/article/connect-sonos-to-a-new-router-or-wi-fi-network

Good and fair point. I had tried what the Sonos website advises. However I have not tried changing the SSID. I will try this but unsure why it is so complicated when I’ve only changed provider.

Unfortunately, things cannot be too “simple” or any kid on bike could access all of your data.

Installing the old router’s SSID and password in the new router is as simple as it can be. Even this can be nasty because the wireless clients will be aware that you changed the router. Some clients will raise a fuss over this, some will not. If a client raises a fuss, simply delete the wireless network from this client and and sign on again. This will satisfy the picky client that you knowingly meant to change the setup.