Perhaps see if this link will assist you to get things sorted…

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

It’s usually best to wire one Sonos speaker to the new router and power cycle the other Sonos speakers/devices. Then remove the old WiFi credentials from the Sonos App ‘Settings/Systen/Network/Manage Networks’.

Then use the ‘update networks’ option in the App to add the new Sky WiFi credentials to your speakers. You may also find these two links helpful:

• https://support.sonos.com/en-us/article/choose-between-a-wireless-and-wired-sonos-setup
• Sonos on WiFi Mesh
   

I have the same issue.

I tried connecting my speakers by plugging into my Ethernet but when I try to update the network it prompts me to unplug and then the speakers are not picked up on the network 

I have tried factory resetting the speakers and following all the steps advised on sonos guidance. I have also made my wifi security level lower but it still won't find my speakers.

A sonos advisor suggested that as my router is WPA2 / WPA3 the speakers are not compatible...but I have seen other people connecting their speakers with this router ..is there any way around it?