how to connect an AirPort Extreme with a new router

You asked the same question previously and it was answered.

how to connect an airport extreme [2012?], with new router from local att provider.

We've now answered the same question two times. The answers are not going to change, so there is no need to ask a third time.

A new router will likely far outperform an AirPort Extreme with much better WiFi security as well. Not sure what you might be hoping to gain by connecting an older AirPort Extreme to your new router.

The AirPort Extreme cannot connect to your new router using a WiFi connection, if that might be what you are thinking. It must connect using a permanent wired Ethernet cable connection.

Can you provide some more details on your goals for the AirPort Extreme?

What model number of AirPort Extreme do you have? We ask because about half of the AirPort Extreme versions are now considered to be obsolete.

The new router which is not Apple since Apple stopped router production in 2018 must be plugged into it with ethernet.. or ethernet replacement like powerline adapters. There is no possible wireless connection between them.

The Airport must be reset to factory and reconfigured correctly to correct settings as Access Point or whatever you still need it for.

Why are you still using the Extreme?

What role is it playing in the network?

To help we need full sentences with info in them.

Edit

Beaten again!! Morning Bob!!

Howdy LaPastenague!