I recently changed to a Linksys SPN router Model No SPNM60  through Toob Broadband  supplier.

Everything reconnected perfectly except Ring doorbell 4. 

After 2 days and numerous phone calls to Ring, Toob Technical team( broadband supplier), Linksys technical team,  it turns out there is a "known" conflict error. It would have helped immensely if Linksys make people aware....

Hopefully both Ring and Linksys can speak to each other and rectify this, something my Doorbell and Router are annoyingly not doing at present....