Try simply clicking the start button and then just type ...
cmd
The command prompt option should appear at the top of the listed results.
Right click that and choose "run as administrator"
In the "elevated" administrator's command prompt window try typing the following
netsh int ip reset resetlog.txt
hit enter
then type
netsh Winsock reset
hit enter
then type
exit
hit enter
Restart your computer
See if that works for you.
It occurs to me that I have very little recent experience with "Avast", so....
I don't know if has a firewall component, nor if its' removal might have impacted the normal operation / settings of the built-in Windows Firewall.
Additionally, something you might double check....
A while back, I had a particular headache as a result of a security product from a company called Sunbelt Software named Vipre.
When I removed it, it left a remnant that required my attention, so....
Right click the start button and from the context menu select Device Manager
Typically, in the Device Manager window, any problem component will have been flagged with an icon indicating a potential issue and almost automatically expanded by default.
Have a look there and see if Device manager is showing any issues, paying particular attention to "Network adapters" and the area called "System Devices" as some Software Programs will install components there that simulate actual hardware.