Help with credit card Terminal

First, this probably isnt the right area to post this. Sorry, but im desperate. You users seem to be adept with computer related equipment. We have a credit card processing unit and everything was working good until we went from roadrunner cable to DSL. Our credit card terminal now will NOT connect through ethernet..only dial up. We have checked our router that it is plugged into and the port is flashing so we know its connected. All of our laptops connect to the net all day long without problems .Anyone have any suggestions!?!? Thanks in advance!