Airport Extreme, port forwarding, wrong IP address

I would reset the AE to factory and start over.. this kind of setup calls for a whole new clean setup.

Your new modem is a router.. the AE should be in bridge modem..

Go to the network tab. and ensure it is setup for bridge.

All port forwarding will take place on the comcast xfinity.. the AE is now a dumb WAP and switch.

The actual place where the routing happens doesn't matter a great deal.

My AEBS is connected with 2 other extremes to cover my house, should my central base still be in bridge. Here is what my airport utility looks like

That is fine.. the AEBS that is the main router now, will simply function as the central connection for all the other apple wireless routers you have.. the fact that it is tied back to the Xfinity will make no difference.

You should in fact be able to make that one simple change.. router to bridge.. on main airport.. then you need to power down everything..

Power up then in order.. xfinity.. AE main.. wait a couple of min for each.. then all the other airports can be started up.. everything will move IP as the xfinity will be different.. but the otherwise changes will be minor.. at least that is the theory.. as anyone who does network will tell you, then the voodoo factor of wireless steps in.

And is there any way I can connect to my xfinity modem/router directly without ethernet cables?

Yes, you can connect to it via wireless.. just switch one of your computers over from the current wireless to the xfinitiy wireless.

Although I might be misunderstanding the point of the question.

If I do do a factory reset to my airport extreme base, will it be hard to reconfigure? I am okay at it, but have never done it myself.

Try the simple method I suggested above.. just the swap from router to bridge might work. If not you do need to be prepared to do the setup again.

You have probably never used it.. but can I suggest before you start playing you export your current configuration for everything.

I will give you a separate post.. rather than expand this forever.

can I get my xfinity router to connect to my airport extreme (the one that is connected to all of the others) to appear on airport utility?

No, apple is apple and everything else is non-apple and never the twain shall met.. Everything else in the world uses HTML.. ie you open it in your browser. Some might have special setup apps, but only Apple have no HTML or CLI setup. Only Apple works with airport utility.

Before you configure.. save the previous configuration.

This is not hard.

Open the airport utility..

Hold down the option key and double click on the basementairport (this seems to be the main one in the setup).

Now I have to show what my system looks like.

If I hold option + double click the TCgen4 I get this.

You could also just click the router, and then click edit from the summary screen but you do not get this summary as above.

You can now go to the top menu area of the airport utility.. and select export the configuration.

That means you have now got a copy of the existing setup.

Turn off all the rest of the units.. just work on the single main unit first.

I would take special note of all the names you have used on basementairport and try just going to the network tab and change from dhcp and nat to off bridge mode.. and apply it.. wait for the system to update and connect back.. if it goes well then everything will still be working and you will still have internet on that computer.. now you can go around and turn on all the other airports and they should all work fine.

If it doesn't work, you will need to factory reset and start over.

I like your naming so stick with that. (except the express with spaces in the name).

Again do each item on at a time in order of connection.. wireless extend last.

It will take you a bit but save the configuration on each item so you can always go backwards if you have to.

yell if you need help..

My email will be stripped from a post but you can pick it up via my webpage which oddly enough is fine.

https://sites.google.com/site/lapastenague/

All port forwarding will be done on the router. .ie xfinity.. as the Airport is now a dumb AP and switch..