So, the issue goes like this: whenever I restart my PC with internet cable plugged in, Avast Premier seems to be blocking all traffic. No apparent issues can be found in network configuration, and icon in Taskbar shows that connection has been established. However, no application is able to access internet, including Avast itself, even with firewall and other features disabled. When I unplug the cable and connect it again, everything works just fine. Only minimum Avast installation has no issues (File shield, Behaviour shield and Web shield).
My network adapter is Realtek PCIe GbE Family Controller. If I connect to internet through wireless TP-Link router, everything works just fine, but speed is only 100 Mbps vs 600 Mbps when plugging cable directly to PC.
My HP Notebook also has Avast Premier installed, and everything works when plugging the cable to it. No issues at all. It’s just my PC acting weird like this. No idea why.
It doesn’t matter if I set it to Private or Public. As far as I can tell, anything beyond Minimal setup causes this issue. It persists even with Firewall disabled. Disabling Web shield and Real Site isn’t helping either. Weird indeed. Why would Avast block its own traffic?
I looked at firewall logs, it seems that Avast is blocking gateway access for some reason. I haven’t managed to find a way to whitelist it yet.
For now I’m using Minimal setup with Comodore firewall doing the actual job of maintaining firewall.
I’m considering getting a dedicated Network adapter, just in case Avast might be conflicting with Realtek driver. That’s the only explanation to why Avast causes no problems on laptop or when accessing internet through router.
Don’t forget that everything works just fine once I reattach the cable.