Hi Linkes,
Don't know if this is still an issue, but here my suggestion.
Your problem sounds firewall related to me. After playing around choice of two fixes, one simple; one more involved.
Simple fix first. Open Avast; goto Firewall tab / Firewall Settings sub-tab. Change WORK ZONE to HOME ZONE, this should allow others on your network access to your pc.
The other fix involves changing the settings for the WORK ZONE.
Open Avast; goto Firewall tab / Application Rules sub-tab.
From the listed Applications, expand Microsoft Corporation and System;
On the bar chart near “Friends in and Internet Out”, click the fourth bar.
This will change the access description to “Allow outbound access to the Internet and inbound access from Friends”, and should allow other's on your network access to your pc.
Hope this helps,
Simon