You can only use Direct IP if the host has the ports forwarded. You can do this in your router. PW needs these ports
although I think only some of them are really important, the others are just for GameSpy, which has closed the service for PW a long time ago anyways.
The easiest option would probably to use a service like Tunngle since it will fake a LAN, no port forwards needed, or just 1. I don't know, maybe Gameranger does the same. Btw, your EXTERNAL IP is this one: http://api.champany.de/j/?ip
Often there's just the local ip (192.168....) shown ingame which is of course useless for online gaming.
Can you play CEP with Gameranger? Or does Gameranger just start PW by itself? Then you probably cannot play with Boosterpack MP and of course not with CEP as well. But playing with direct IP connect and open ports should always work.
To make sure you're currently running the same mods, check the line at the right bottom in the options menu.
Finally, if you attempt to use the Internet Server Browser, PWServer.exe crashes. Don't do it, it doesn't work anymore.