This has never worked in any version of Firefox I have used. My laptop moves from a corporate network to my personal home network. From home, I can enable my VPN service to connect once again to the corporate network. Whenever I am connected to the corporate network, I must select Tools->Options->Advanced->Network->Settings->Automatic proxy configuration URL, oonly then I can browse from within the corporate network. Whenever I am at home, I must select Tools->Options->Advanced->Network->Settings->No proxy. Ideally, Firefox should be able to automatically switch between these two settings when I connect or disconnect from my corporate network without requiring me to manually configure this setting every time. At the very least, Firefox should be able to be configured to try connecting via the proxy first and fall back to using no proxy if the proxy is unavailable. I have already tried the Tools->Options->Advanced->Network->Settings->Auto-detect proxy settings for this network and Tools->Options->Advanced->Network->Settings->Use system proxy settings Tools->Options->Advanced->Network->Settings->