Same issue with the last build 14965 (Released Wednesday)
After install of build 14971 still download problems.
Problems gone after disabling Avast
My web shield AND EVERYTHING ELSE is turned off, but despite renewing my subscription in July, your company appears to be trying to force me to pay again! I have contacted support, but in the meantime am uninstalling Avast and downloading a free antivirus program as I need to work!!
Post your ticket-ID.
I have also an open ticket for download problems:
https://support.avast.com/support/tickets/563093
I got a report in the Japanese forum that claims both Web Shield and Secure DNS caused this problem.
And what is causing the same issue in other antivirus? Avast is not alone here…
Win 10, of course…
But Avast have to fix this before Win10 stable build get released, or there will be a mess. :-
“Slow” ring beta also has this issue, I doubt Microsoft will do something about this considering the remaining time.
I’m on build 14936 and set the update sequence to the slow ring. Avast is working quite well. 
The OP in the Japanese forum reported that he/she had build 14965 on slow ring ???
But Avast have to fix this before Win10 stable build get released, or there will be a messMicrosoft is the one who needs to fix it. It is (almost) not possible for avast and other av vendors to do something about it as the problem is W10 and Microsoft keep changing things.
build 14936 was the last build where you could use a third party AV.
Anything after that release required that you only have Defender installed.
Indeed.
I’m on slow ring and did not notice any issue…
I can hardly believe, but…
After install of build 14986 NO download problems here.
Can one of you confirm that ?
I am running with enabled Final Avast free 2.3.2280 (build 12.3.3154.23) and vps 161208-3 (vps edited)
You are using a old VPS version.
Sorry, changed