Connection issues with Airport Extreme

We need specifics ..

I turned to my router.

What router?? Make and model?

What model is the Airport Extreme?

What OS is on the computer you are using for the setup.. is it really Snow Leopard??

You seem to be using router for various different things.. we have a modem a router and AE?? And I think occasionally you refer to modem as router and airport as router.. so it is really hard.

As soon as I connect the router I lose the wifi signal.

How did you connect to the router?

What wifi signal did you lose.. from the router or from the AE??

The airport utility shows either the modem or the router connected but never at the same time.

The airport utility cannot show anything to do with the modem.. it cannot be an apple because apple do not make modems.. also we now have modem and router.. so I am confused.

If you plug the airport into the modem (is it a router or not??) then the airport must be in the right mode.. that means.. to a modem it is router and to a modem router it is bridge.

Please reset the AE to factory and start again..

This time do the setup from something like IOS if possible.. it is superior to the Mac.

modem - motorola sb6141 cable modem

Here is your problem..

It is almost absurd and I cannot explain the logic.. there is none.

SB6141 is subject to more issues here than any other network device (especially if you add the other SB models. )

This started with the last version firmware for older series.. 7.6.4 and mostly affects the AC model AE and TC.

There is no fix.. normally it will be bad from day one.. but your situation is also far from unique.

The AE is also not as reliable as it should be.

You did not answer which model AE you have.. but let me assume you have the AC version. (tall one).

Make sure it is in router mode.. this is absolutely required.

Go to the airport utility and ensure you connected as router by clicking edit and going to the network tab.. It must show dhcp + nat.

Go to the Internet tab. it must show DHCP.

It also has to show your public IP address and the correct gateway.. mine is different so I cannot show you that.

Go to the wireless tab.. it must show create a wireless network..

Assuming all of these are correct.. then your AE is now faulty.. return it to apple for replacement if in warranty or you have applecare on a computer/ipad or apple TV.

Ok.. the issue then is entirely the poor SB6141 and AC version TC combo.. one of those mysteries of life.

Replace either the modem or router.

I am not in the US.. so read a thread like..

Time Capsule Intermittently Will Not Connect to the Cable Modem