First of all, if you have trouble with game speed, rename the "music" and "midi" folders in your Dune 2: TSHA directory. This will disable music, but free up your resources. Midi music uses a lot of CPU power, and the MP3 music takes a lot of memory.
Next, if you actually can't get the game running, I may not be able to help you much. I tested it on an awful lot of systems and didn't have problems, except for a minor graphic glitch with placing unit build queues on some older graphic chipsets.
Regarding networking, the following will remain forever true for that version, since I had little community support and no longer wish to think about it much:
- There are still a couple minor bugs left in there which might cause crashes after playing for some time (usually at least half an hour). I've had longer games than that though, and it's stable for the most part.
- Finding an online server is hit-or-miss in terms of functionality. Your best bet is to get your friend's external IP address so you can connect directly that way across the internet.
- If you have firewall issues, I can't help you. The port you need opened is 10191, that's the best I can tell you. I've never even been able to get confirmation from anyone that they got this working through a firewall.
- More than two players in a single game will probably never work, so don't try it.