AC1200 wifi router model R6120

Hello,  I hope someone can help because I really don't understand why my router is stating, "Something has changed since the last time you connected.  We need additional information to complete the connection."  Then  it asks me to enter a security key.  There is no security key of any sort with my paperwork and I have tried using all the passwords provided when the router was new and all the passwords that were used (changed from those given) when we set up the router.  I have no idea what to do next.  The router was set up in early 2021 and until recently seemed fine, although the wifi is rarely used as we are mostly ethernet.

Thanks.