Receiving error 'This address is restricted' when using Firefox when connecting to a device not using port 80

Error Message

When connecting to a device that is no longer using port 80 with Mozilla Firefox, you receive the following error message:




Open Mozilla Firefox.

In the address bar, type: about:config


This will take you to a page that looks similar to this:



In the search box type:

You may find that the search doesn't find anything, if this is the case, follow the steps below, if it does find a matching result skip the steps directly below.

If no result is returned when searching for: then you will need to make a new string. To do this:

Right click in the blank search area and select 'New' then 'String'.


You will see a pop-up box appear asking for the new string value. "Enter the preference name". The name needs to be ''


Once this has been entered, select 'Ok'. You will then get another box pop up saying 'enter string value'. This is effectively asking which port/s you wish to open.


Within this box you have a few ways of specifying the ports you require. These are:

Simply just one port number i.e. 116

Multiple port numbers (please separate the ports using a comma) i.e: 116,554,81

limited Port range i.e. 81-116
Full Port range i.e. 1-65535

This should now stop the error message being displayed upon connecting to your device.

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