To play a multi-player game every player's IP Address must be known to DN Map Loader. Each person who is playing in the game will need to do the following in their copy of DNML.
Open the Preferences window and click the Multi-Player tab. In the name field type in the name you would like others to see when you are playing. If you have more than one IP Address configured on your computer select the public one in the popup. Enable Rendezvous to have the address of every player on the network automatically filled in. You can also add and remove players manually as needed. Every player in the list whose Include checkbox has been checked will be included in the game. Note that Duke Nukem will not finish launching until all Included players have been found.
Close the Preferences window and select the map you are going to play in the list of maps (every player must select the same map). Click the Play button. Duke Nukem will launch with the files and settings needed for the selected map. When you quit the game Duke Nukem will be restored back to it's previous state.
If a map fails to load using this method, please see When It Doesn't Work for possible solutions.