Home web server and gaming server setup for a pc on my lan?

I have a web server running on port 80 of a pc on my lan. It also runs some docker vm's running a minecraft java server and some other applications.

i am using port 80,25565, 7000,9000,10000,20000 for the various application on the server.

I had port forwarding set up on my nighthawk router with my cable modem.  How can I use my Nighthawk to act as my router now that I have the at&t air wifi router/modem in place of my xfinity cable modem?