Hi loopingz
I had the same problem (if I understand you rightly). I wanted to hold a multiplayer race between myself and One other person. In the early days of LFS this was straightforward, a fancy host name, a password that only you and the other party knew and hey presto, you had your head-to-head race.
Then, mysteriously, some three years or so back, after an upgrade patch the option disappeared and we got "timed out" and on asking for help, were directed to explore the mysteries of "port forwarding". That proved beyond us. So, unfortunately, our head to head battles were ended unless we found a deserted track on Multiplayer which allowed the Fox cars.
At intervals we came back to the LFS forum to seek help but no easy directions to solve port forwarding was to be found.
Recently, two things helped.
One, found a friend who knew about port forwarding.
Unfortunately his explanation was still the kind to induce a glazed look in my eyes!
Secondly, a piece of software called "Teamviewer" became available. With this he could be at his own computer, but get onto my computer (with my password and therefore, permission, and in barely two minutes solve the mysteries of port forwarding for me. I now have head to head racing via multiplayer at my disposal.
On the one hand, I am none the wiser for he was so fast as his mouse whizzed over my screen to sort out "pf" I could never remember all the steps but the problem is solved.
next step. Find someone who knows about port forwarding.
Get the free software of "teamviewer" and see a miracle unfold before your eyes!!