I have got Avast Premium Security and Windows 7 - it’s blocked my internet connection today!! Help me!!
Check your Firewall settings and if profile is set at Public, Try setting your Firewall Profile to ‘Private’
I disable Avast and all work! Prоblem is Avast (as well as in 2012 year) - it is new bag Avast.
Setting up Firewall Application Rules in Avast Antivirus
https://support.avast.com/en-eu/article/Antivirus-Firewall-Application-Rules
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NOTE:The Network profiles control the settings which determine how strictly Firewall protects your PC.
Private: a lower level of security suitable for when your PC is connected to a trusted network such as your home or work network.
This profile enables better connectivity, and permits all communication within the network.
Public: a higher level of security suitable for when your PC is connected to a public network such as in a cafe or airport.
Because public networks present greater security risks, no incoming communication is permitted when this profile is set.
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also see post here from BWhit https://forum.avast.com/index.php?topic=227130.msg1505540#msg1505540