Is your firewall / network profile in Puplic or private mode?
How do I find this out?
Firewall - Network profiles >> https://help.avast.com/en/av_free/12/settings_fw_profiles.html
If I go to Firewall via Settings > Components > Firewall > Customise I only have the following options Default rules, Preferences and Packet Rules.
https://www.avast.com/faq.php?article=AVKB25#artTitle