Or it might be that someone inadvertently changed the Firefox proxy settings. The error shows up when your proxy configuration either on your PC or your browser gets changed. But, more commonly your browser will have full access to the internet without the use of any proxy server. In some cases, a private internet service provider (ISP) that you use at home may also require the use of a proxy server. Outgoing internet traffic is filtered for employees who may be trying to access inappropriate websites.Incoming internet traffic is checked for malicious attacks.This proxy server is part of a two-way form of communication. Companies often use a proxy server to 'filter' all internet traffic. The most common use of a proxy is inside a corporation. However, there are common fixes to this proxy server connection problem if you know where to look. People often assume that it's an internet connection problem. The result of this error is that you won't be able to access the internet at all.