It means that UPnP is disabled on your router.
What happens if I disable UPnP on my router?
First of all, there is a lot of ambiguity surrounding UPnP. I assume
that you mean a device that implements the Internet Gateway Device
profile. What happens is that it will not be possible anymore to let
applications change firewall settings on the router anymore through
UPnP. Some applications will not like it, since they depend on it.
Other applications will work, but might not perform as much as before.
A good example is Live Messenger. If it can't use UPnP for file
transfers it will use a proxy server from Microsoft. Of course this
proxy has probably a lot less bandwidth than your own connection.
You can keep it disabled if you've configured port forwarding. When configuring port forwarding, make sure that:
- External (source) IP is 0.0.0.0
- Local (destination) IP is the IP of your desktop. You'd want to set up your desktop in such a way to always use the same IP. There are many guides for this easily found.
- Both external and local ports to be 18080
- Protocol to be set to TCP
- The configuration is saved and enabled
If it's set correctly and not working, one reason could be your ISP (as it was in my case). Every ISP has a limited number of IP addresses he can give out, so sometimes you could be sharing an IP with other people. If that's the case, your node will not be seen from the outside.
You can check this. Open your router configuration, and find WAN settings. There, you should see your external IP as reported by your router. Use some web service to check your IP "from the Internet", like this one. If it's different, it likely means that you're behind a double NAT. What you can try to do is call your ISP and tell them you're having trouble configuring port forwarding. They might set you up to have an unique IP, and from that point onward you should be seen from the Internet.
To test if successful, you can scan your port 18080 by using some web service like this one.