ericjung
commented
2 years ago FoxyProxy Plus had this feature some years ago. Unfortunately, the ability to get the intranet IP address from a browser extension was removed from Firefox. As far as I know, there is no way to get it anymore. So, this feature is not technically possible. I am open to being corrected, but closing this ticket unless I get other information.
For many users, the choice of the proxy is not determined by the URL they are trying to reach, it's determined by the network they are on. For instance, a 10.0.0.0/8 address would indicate an office whereas 192.168.0.0/16 is probably a home network. Yet 192.168.49.0/24 is probably when they are using Android NetShare and need a proxy. Please consider adding rules where the presence local address (IPv4 or IPv6) in a specified range determines whether the proxy is used.