You may want to try again, it's ok for the Airave to act as a DHCP server even though you have a router also doing this, in short the modem is giving an IP address to the airave, and the airave is giving one to the router. after following the steps above which lights did you see on airave, which color were they, and were they solid?
I tried what you suggested.
I was able to log in to the airave and change the settings. I also told the airave not to be a dhcp server for my network since I azlready have a router doing that. I wasn't getting an internet connection, so I tried to login to the airave again and I could not access it using the IP address that I assigned to it or the default IP address. I pressed the reset button for 15 seconds and I still cannot log into the airave. I had to connect everything the way I originally had it to get an internet connection.
you can reset to factory setting by holding the Reset button for 15 seconds. and with using Comcast you may have to login to airave and specify the computer/router's MAC address for a broadband connection while it's connected between the modem & router..
Having not tested this personally I cannot say, however the expectation it to emplace the device/antenna in a location which will always have GPS signal available.
If the broadband is solid and he has no GPS why would he do these steps because your system won't even see the airave on your servers without GPS being solid? I don't understand why his GPS light isn't blinking green. I've never seen it do anything other than solid green or blinking. Mine only goes off after a reset or reboot and after a few moments it's blinking before going solid. The mobile light sometimes blinks but it's mostly solid too.