Just wanted to say thanks again. Not sure how I did it, well sort of I am but no where close to the understanding part. But sort of. I have a lot going on this past week into next and sort of trying stuff on the fly to stay busy.Yes that is all there is to it. Your 2600 router will be doing nothing more than converting packets from wireless to wired and sending them unchanged to the T-Mobile box.
The separate AP allows you to deploy a strong wifi signal where the users are, with the T-Mobile box remaining placed for best cellular signal.
Configured for "passthrough," "bridged," or "dumb AP," the AP box will do no DHCP assignments, routing, NAT, or firewalling. Those functions are all handled by the main router. The main router sees users of the AP as a group of wired clients.
This means no special configuration of the main router is needed to add one or more dumb APs to the network. They are served like wired clients.