First I will start out by insisting that you read the ID section of eMule's documentation before reading the rest of what I have to say.
Since most people miss things when they read, I am going to recap some of the more important points:
If the ID is high, it does not matter how high it is. An "even higher" ID is not better or offers any advantages.
No IP is known of the machine eMule is running on therefore all requests like queue or connection requests to this client have to be routed over the server, the low ID client is connected to. This routing causes considerable amount of CPU load on the server thus reducing the maximum number of users the server can cope with. Lugdunum's servers limit the number low ID users or even ban them at all.
Ok now that the basics have been covered, let’s continue.
Now to discuss the most common reasons for a low-id
If a router is being used, the problem is almost always dealing with ports; the ports must be open and forwarded to your LAN-IP.
Many ISP’s are starting to block/filter ports. This is bad for P2P users, as they are either denied service to the networks or in eMules case, stuck with a low-id.
Improperly configured firewalls are also a problem.
Windows XP firewall is enabled or not configured.
"Your port XXXX is not available; please check your network config"
Before doing any of these steps, disable any firewalls you have installed, to rule them out as possible causes of error.
This is a common message many users get. It means that eMule does not have access to the port listed in place of "XXXX". Have a look below on how to solve this.
Router: most likely you have not configured your router correctly, double check that the ports you are forwarding are the same as the ones listed in eMules Preferences->connections. You should also check to make sure that you are forwarding the ports to the correct LAN-IP. To do thing, go to start->run-> and type “cmd” then press ENTER. A black command line window will appear, here you must type “ipconfig” and your IP will appear a few lines down, it is labeled “ip address.” Those instructions should work fine on a WinXP/2K PC, but if you are using Win9x you are going to want to replace “cmd” with “command” and “ipconfig” with “winipcfg”
Standard Connection: You should check to make sure that your modem does not have a built in firewall, and if it does, open the ports needed for eMule. If no firewall exists on your machine and your modem, use the steps below.
For either router or standard: if the above steps do not solve this issue, you are going to want to try to change your ports, its possible that your ISP has them disabled. I usually suggest a port-range around 27015, as these ports are used for a lot of online-multiplayer games, and are usually not blocked. If you change these and you have a router, make sure to change your routers configuration too.
