I tried downloading the new beta and the latest main version of avast IS.
(Too) Many users suggesting simultaneously may be counterproductive, but that's
EdisnaecoIMVU's decision.
Anyway, may I suggest, when trying Avast, to use a more "conservative" way?
0_ Do you have all Windows updates installed and Windows (re)validated?
1_ Try the latest STABLE Avast FREE (not AIS).
2_ If "1_" doesn't work, uninstall, reboot, try the latest beta of Avast FREE (not AIS).
3_ If previous steps won't work for you (for whatever reason), then AIS probably won't work either. If you got the FREE STABLE to work, then uninstall and try AIS STABLE. If the FREE BETA was the one that worked, then uninstall and try AIS BETA.
For any install, reboot. For any uninstall, use the clean uninstall utility and reboot.
Note that in "Windows Safe Mode" your connection is not supposed to work. You would need "Safe Mode with Network". Under those modes, Avast is not supposed to be active, so there might be a different issue if you still can't connect.
Any other firewalls? Can you delete older Windows Firewall rules? And when you re-create the Firewall rules, whether manually or automatically by the program(s), you should try to connect, reboot, try to connect again, reboot, and try to connect once more. (I know, it seems "too much", but it had worked for me in some cases).
BTW, after
each reboot, give it time to even try it. Windows UI may seem to be ready, but the processes/services most probably are not (Windows Task Manager -> Performance, and/or "Resource Monitor" might give you "some" indications).