If I change my home network from PRIVATE to PUBLIC, or vice versa, I have avast firewall set to notify me of network change. (Automatic Profile Switching)
See attached for setting to notify below:
This setting is hidden, in the geek:area section of avast antivirus. To get there, go Menu>Settings>Search>enter geek:area in box and press enter.
Is this what you are talking about? If it is, then what DavidR said would come into play.