Because of the way it is configured you won't be able to access the Vigor from the Airport side of the network.

If you add a hub or switch between the Airport and the Vigor and connect your Mac to that then you will be able to use the 192.168.2.x address range and connect to the Vigor while it is still connected to the Airport.

As bartern has explained, it doesn't matter whether the Airport or the ADSL line is connected, as long as you have a copy of the firmware then you can still upload it.

If you want stats on the live connection then using the method with a hub or switch will work.

Regards Alan