Not all routers Support Loopback, some have the option on the web config page to turn on/off.
What is Loopback?
If you say ran a Web Server from one of your computer on the network (LAN) and opened the port to allow people from the Outside to view this server - this works fine for all people outside if they put in your IP / NO-IP Name. If you are inside the LAN (which you would be) and put your External IP in the web browser but got instead your router config page instead of the Web server - this means the router is not performing LoopBack.
This can be a problem for running a Server such as Mir3 as you the host will not be able to play yourself, due to the way MIR3 has t lock onto an IP for the gates.
Solutions?
Personally the easiest way is to buy a router that supports this, Linksys does and many others, lets say that the ones NOT Supporting Loopback are in the small numbers. The other way is to run 2 gates, one for External and one for Internal.
