How Routers affect the WebUI

I (re)created an image that might help some people understand how having a router between your µTorrent machine and the internet might affect your webui:

For most of you this image will need clarification.

First, please note that the ports and IPs we use in the image above and the description below are examples.

• To find your LAN IP press the Winkey and R and type cmd /k ipconfig. Now look for the IP(v4)-address line.
  If there multiple such lines it is likely the IP that looks either like 192.168.x.x or 10.x.x.x and it is often listed under the first Ethernet adapter.
  
• To find your Internet IP go to http://www.WhatIsMyIP.com
  
• To find your µTorrent port look in the Connection Preferences of µTorrent (if you enabled the WebUI alternative listening port use that).
  

Port forward

Without a port forward a router simply does not know what to do with a connection coming from elsewhere on the internet. So anyone trying to connect will deadend in your router (see the orange line).

By creating a port forward in your router for port 34555 (our example!) you tell the router that when a connection from the internet arrives at port 34555 it should be forwarded to 192.168.0.1 (the LAN IP of the machine running µTorrent). Now anyone trying to connect will be able to reach your µTorrent machine (see green line). Please note that firewalls on your µTorrent machine might still block connections.

Instructions on how to forward a port in your model router can be found here.

Router Loopback issue

When you try to reach the webui from the machine running µTorrent itself or from a machine in the same LAN you should use the LAN IP (see blue and teal lines).

If you instead try to use your own Internet IP your router will see the internet IP and will think you are trying to connect to a machine elsewhere on the internet. But once on the internet the connection will deadend because it is coming from and going to the same IP (see red line). Only about 5% of the routers out there have a workaround for this which loops your connection back, via your portforward, to the µTorrent machine.