You will probably need to run netconfig again and set your DHCP to the gateway server name and ip--even though you'll have a static IP of 18.104.22.168. This way, it looks for the proper location to get its IP and will be able to obtain its static IP. I could be totally wrong here, but I think this should work.
Either way, you'll have to run netconfig again, and edit your /etc/resolv.conf to add the proper DNS entries:
search (domain name--most likely your gateway server)
nameserver xxx.xxx.xxx.xxx primary DNS IP
nameserver xxx.xxx.xxx.xxx secondary DNS IP
Since you're connecting to a gateway server, you should use your gateway's IP address here. Like I said, I'm not 100% sure on this, but that's how I would start. Hope this helps