Since I'm using it, I seem to be unable to host games. When I host, the game is pinging for all the players (I once turned a server on for half an hour and nobody came, but it seemed that there were quite much JJ2 players online). I don't use any firewall. My modem is Motorola SurfBoard SB5100 and my operating system is W98. I have connected the modem via Ethernet card. Is there a solution to this?

There is something blocking the incoming connections. If you are sure that the cable modem is directly connected to your computer and that you don't have a firewall, you have to contact your ISP for help. Tell them that you need port 10052 TCP and UDP open.

Are you able to join other games?

Yes, and I time out almost never.

In that case it would sound like you don't have some of your ports open.

Then... I need to call my cable provider?

Only if you are sure that you don't have any kind of firewall. Remember to tell them what ports you need to have open (10052 TCP & UDP).