Did you change the dhcp options to reflect the new IP of the appserver (option 211 or 212) ?
Or if it's not set there, is it hard-coded in the gentoo image? if it's set there it's the BL_AS environment variable.
I did change the DHCP options with the new IP. It must be in the gentoo image like you said.
It should only need to be in 1 of those places. You'd only need to hard-code it in the gentoo image if it wasn't being picked up from the dhcp server.
if you boot into the gentoo image and then ctrl-c out of the bmi you should be able to find the BL_AS setting in one of the startup scripts. or look in your mkgen2img.sh script.