First, is the list problem fixed? Are you able to access the server list from within your game, as well as make games appear in the list when you host?
I already explained how to fix the timeout problem in my other post, but I'll try again. Consider the following image.
Your router (represented by the blue gateway in the image) acts as a firewall in addition to splitting the internet connection on your network. This means that you are able to connect to other JJ2 servers, but they cannot send data back to you. This is why you time out after 30 seconds.
To allow the JJ2 server to send data back to you, your router must be configured to "forward" the connection. This will make the router send the incoming JJ2 connections to your computer, instead of blocking it as in the image. Every router has a different specific method of configuration, but it is usually done through a web page accessible by any computer on your network.
With Windows 98, go to the Start Menu, click "Run", type "winipcfg", and press enter or click OK. This program displays your current network configuration. There are two addresses you need to note: your IP address, and the default gateway. Write these down and close the program.
Now in your web browser, enter the address of the default gateway. This will bring you to the web based configuration tool. From here, you will need to log in (the default password is usually "admin"), and find a configuration area called "Port Forwarding" or "Virtual Host" or "Special Services" or "Port Triggering" or something like that. If you can't find it, you will need to read your router manual.
In this configuration area, you will be able to enter an outside port number, an inside port number, an IP address, and possibly a trigger port number. For all three port numbers, enter 10052, and for the IP address enter the IP address that you noted previously (not the gateway address). Now save the configuration.
You should now be able to play JJ2 online, as well as host games. If you can't, your computer might have a software firewall installed. You will need to give JJ2 internet access and hosting access on ports 10052, 10053, and 10054. If you don't know how to do this, consult your firewall documentation.