Avast Firewall blocks my internet completely

[REDACTED]

Avast Firewall suddenly blocks my whole internet without any reason.

I just restarted my PC and suddenly I had no internet. After 1 hour of searching I discovered that my Avast Firewall was active, as soon as I deactivated it, my internet came back up.
It might block my router for whatever reason? (I don't get a "decent/normal" LAN IP, when the Firewall is active)

After starting my PC again today the same thing happend. Avast Firewall just blocks me out completely from my network without any reason or changes to it.

Using:
Avast Internet Security
Version 12.3.2280 (build 12.3.3154.23)

[Asyn]

It might block my router for whatever reason? (I don't get a "decent/normal" LAN IP, when the Firewall is active)

Which router..?

[Rednose]

Do you by any chance use a VPN and/or have you updated Avast just before this started to happen ?
Try this :

Avast - Tools - Firewall - Settings - Network profiles - select the network profile(s) (one by one) and click "delete" - Ok.

When done reboot your system.
Avast will now recreate any network profile again when needed.

Greetz, Red.

[REDACTED]

Which router..?

Sorry, meant modem. (Fritzbox 7362 SL)

Do you by any chance use a VPN and/or have you updated Avast just before this started to happen ?
Try this :

Avast - Tools - Firewall - Settings - Network profiles - select the network profile(s) (one by one) and click "delete" - Ok.

When done reboot your system.
Avast will now recreate any network profile again when needed.

I use a VPN (Squidproxy on my own server) only with my browser. Not with all of my internet traffic though.

I didn't change anything before the restart but I THINK Avast might have had an update.

Ill try what you've suggested and report back with the results, thank you.

[Rednose]

I found out that there is a problem confirmed by Avast with Secure DNS in combination with Fritzbox.
Disabling Secure DNS is the only solution untill this is fixed :

Avast - Settings - Components - Secure DNS - ON -> OFF - Ok.

Avast is investigating the problem.

Greetz, Red.

[REDACTED]

I got the same thing last night all of a sudden internet was gone...so I uninstalled and reinstalled and that fixed it for now...this is the second time its happened to me over the last 4 months. 

[Asyn]

Which router..?

Sorry, meant modem. (Fritzbox 7362 SL)

As you speak German, read here: https://forum.avast.com/index.php?topic=193380.0