Al
Your Default Gateway is the same as your IP address but for the last set of numbers, IE. IP address = 192.168.001.050, your Default Gateway would most probably be; 198.168.001.001.
You should try and make the IP address something over and above .010, depending on how many printers you have, go with say #1 = .010, #2 = .020 and so on.
If you look on your router, along with the Serial #, Mac # there should also be the Default Gateway #. The Subnet Mask and Default Gateway should be a continuation of the same menu you put in the IP address.
Hope this helps, if not let me know, Bob.