I am having this issue as well. Was looking for a bunch of solutions then I saw a comment about someone talking about how they had this DNS issue with their AVG anti-virus. So it made me think to disconnect Avast cause it has blocked my wifi before. And VOILA! I am on wifi again. Def an issue with Avast. Especially if so many are experiencing it.
Just uploaded the dump file named
lockAvastUI.7z to Avast FPV / incoming directory. I meant to say ftp 
Avast is looking at that file right now. Thanks. 
The dump was created using the Core Shields/Behavior Shield "Off for 10 minutes) setting and I never got it to lock internet access but on facebook messages and notifications would not load.
From Avast,
“the fix is in VPS 181113-12 (expected release in 2 hours)”
In 2 hrs, try the update,
https://screencast-o-matic.com/screenshots/u/Lh/1542147735328-63377.png
Once updated, reboot and test.
Myself and the other employees at our company are having the same Avast DNS issue. Avast was also using 80% of the CPU. I uninstalled and reinstalled and it seemed to fix it for a few hours. Now the same problem is happening again. I will have to switch everyone off Avast if this isn’t resolved shortly, we need protection and Internet together.
I also use facebook, so it’s possible that is triggering it. Can’t confirm. Please resolve ASAP.
Thanks
Guys, thanks a lot to everyone who has sent us dumps. These have been extremely helpful and the virus lab team has just (an hour ago) found a problem with one of the recent patterns in the scanning engine. Under some circumstances (and yes, certain links on facebook also match these), the scanner could enter an endless loop and eventually stop everything that goes through it (in this case it was the WebShield component and hence the internet errors).
The team is already building a Virus DB update and as announced earlier it should be out in a couple of hours. We’ll post here once the fix is available!
We are really sorry about this. We have already discussed several ways how to update the code so that similar bugs are avoided in the future - and will continue with that tomorrow.
Thanks again to everyone who helped us troubleshoot it by reporting the details here!
Lukas.
Virus definition version that fixes the issue is: VPS 181113-12
It should be out right now!
Thank you.
VPS 18113-12 was released
Works great! Thanks
still having issues getting error pages when using Google Chrome Browser, please advise?
Unable to access the internet, do not want to disable webshield. Please advise?
Clear your browser cache and do a manual VPS update, I have just done that and it brought in VPS version 181113-13.
Thank you David for the response and update… I have quite a few unhappy users right now, so you can appreciate the severity of it all.
You’re welcome, you don’t say if your or your customers have done a manual VPS update rather than wait for the next time the program actually checks for one.
Previously the VPS Update used to have a setting to change the delay between update checks, it used to be 4 hours which could be reduced to every 2 hours. I can’t find that setting now, I don’t know if that is because the streaming updates happen very frequently.
Thank you! It worked for the most part though downloads take forever when Avast is enabled it seems. Had to reinstall iTunes and it was taking an hour. Canceled that download, and it took a couple minutes. Hope there’s a fix soon! Thank you to all the programmers there for all the hard work trying to fix the issues and fixing the primary issue. Things happen, programs have or cause errors, but it seems to always get fixed, and it’s probably not an easy task so thank you all for your hard work, and hope everyone is having a wonderful evening!
It is still there in (paid) AIS.
Just another straw to try and break the camels back or death by a thousand cuts. I rather think those in marketing have lost the plot if they think that will convert free users to paid.
All they need to do is manually update each time they open their system for activity. For me it isn’t an issue as I’m happy enough with the streaming updates, however they can’t deliver any engine updates, etc. etc.
That said your image is of the Program Update settings when done will also check for VPS Updates.
Rebooting your system and connected to Internet with Avast installed will cause an automatic VPS update in my experience.
See attached below.
Those setting are still available in the Free version.
https://screencast-o-matic.com/screenshots/u/Lh/1542235190920-93420.png
I personally don’t think you need to check every 5 min. but, to each their own.
I’m setting mine back to 120 min.