I'm running a wired 100 Mbps connection to my router and avast will pop-up and announce it has automatically changed the firewall settings (I use AIS) to 'Private/Low Risk Zone' from a presumed default setting of 'Public/High Risk Zone'.
Public/High Risk Zone would typically be used on a laptop when connecting to a public wif-fi, for example. Public setting is not needed or required on a home or private network.
The new pop-up does display the router name and type of network connection every time a cold/restart of system is done whereas the older version (.2272) and earlier did not display a pop-up at all, and only did so when first network connection was found for the first time after a clean install.
Attached box does show an option to notify user about automatic network profile switching; I think this is the source of the new pop-up. Untick that box and maybe pop-up will go away.