This thread will attempt to address the connection problems you might run into with TTopRPG and suggest some possible ways to investigate the issues.

Port number 26010

In order to host with TTopRPG (either as a GM or as a Proxy), you MUST open your router's port 26010 and route it to the machine that is hosting. This requires that you access the control menu of your router and insert the proper entry in its Port Forwarding screen, or Port Mapping, or whatever it might be called. Unfortunately, how this happens varies greatly from one router to another, so I can't offer any recommendations of which screen name to watch for or exactly what to fill in where.

At the very least, I can tell you that if you need to know the local IP address of your machine, you can run a Command Prompt and type "ipconfig". The IPv4 address is what you need to route port 26010 to. This address is local to your network, and will be different from the public IP that clients will see your machine as. For example, my local machine's network address is 192.168.1.100, but my router's public IP address is usually 24.231.195.27 (retrieved via http://whatismyip.com), or something similar, and is what clients use to connect - so in this case, I would forward port 26010 to 192.168.1.100, which causes my router to forward outside requests for 24.231.195.27 to 192.168.1.100 on my network.

By the way, if you don't know the address for your router, usually it is Default Gateway in the ipconfig output. Type that address into a browser and you should get the login box to access your router settings.

Another solution is to just open your entire router port set by allowing your router to DMZ, which is a screen I would imagine many routers have in their menu. To activate it, find the DMZ screen and fill in the IP address of your machine as with port forwarding. This operation routes ALL ports to your machine, and is typically not recommended, since it could make you vulnerable to network attacks. You should make sure to disable this option after you are finished hosting (by setting the address to 0).

Anti-virus and software firewalls

Even though your port may be open, software running on your OS may still block some ports. Kaspersky Antivirus, as an example, has this feature. You'll need to find a way to disable blockage for port 26010 in order to host. Try temporarily disabling the software entirely and see if hosting works. If it does, then you can re-enable the software and try to set the software/firewall to allow port 26010 specifically, if the option is available.

Only the host in the group needs to open its port

Once the host has its port opened and everyone has a public IP to connect to, no other machine needs its port opened. Also, since TTopRPG allows proxy hosting, if the GM can't find a way to open port 26010, it only takes one player in the group that can do so. You can then GM a game through that player by having them Host as Player (Proxy), then Connect as GM to that player. Everyone else connects to the player as normal.

Timeouts

TTopRPG sends a small packet every 7 seconds to keep connections active. Each client sends this packet to the host, and the host sends a packet to every client.

If any given machine doesn't receive a packet within 10 seconds of the last receive, it suspects a disconnect and displays a warning. After three such warnings, TTopRPG gives up and disconnects. This gives each machine 30 seconds to recover.

On slower connections (such as wireless, DSL, and especially dial-up), this problem might occasionally be very prevalent. I can't recommend anything about how to avoid the disconnects except to say that in my experience, it hasn't happened very often. Occasionally internet connections hiccup and fail to transmit for a time. In these circumstances, all you can do is attempt to reconnect after your connection drops. Fortunately, TTopRPG allows you to pick up exactly where you left off (but it doesn't restore the chat log).

Try to avoid hosting campaigns with large graphic files on slow networks (especially if you are GMing through a proxy). The data will eventually reach the clients, but the data transfer will be very slow.

VMWare and NAT vs. bridged

One user noted that, when using VMWare to run Windows on a Mac using NAT to communicate between both, TTop wouldn't host. By changing the network between them to 'bridged', TTop was able to host. This takes up an additional IP address on your network. (added 1/30/10)

More complex connection problems

If it isn't possible for you to open your port because you are behind a complex firewall or a multi-tiered network, I'm afraid there isn't any way for you to host games. Some virtual tabletops offer a way for the software to connect via a server out on the internet that allows machines to handshake with each other, which can get through the complex network problem. Unfortunately, TTopRPG doesn't offer that kind of service at this time.