@RTMC This has nothing to do with internet speed. You should not be passing network traffic through the OC200, it should be an end device, ideally attached directly to a central switch or the router. So it won't affect the speed of the rest of the network.
The second port is really there for trouble shooting, it allows you to connect up a laptop directly while the OC200 is attached to the network. The second port may also allow for the OC200 to be connected to two physically disconnected networks, for dual management, but I've not read of anyone doing that.