We're having this problem, as well. Here's an excerpt from the install log on one of our servers:
01/16/19 13:43:52 advantag Setup - Auth > CInetHttp > WaitForConnect failed - 6 (Couldn't resolve host name)
01/16/19 13:43:52 advantag Setup - Auth > CAuthService::OpenConnection to 'https://bcons-core-sea.ff.avast.com:443/agent/' failed with 6
01/16/19 13:43:52 advantag Setup - Auth > Failed to connect - 1006
01/16/19 13:43:52 advantag Setup - Auth > DownloadInstallPolicyInternal: Connection failed
01/16/19 13:43:52 advantag Setup - Setup > DownloadInstallPolicy nResult=1006
Running Windows 2012r2. Firewall is temporarily disabled and DNS, etc. is all working properly.
Help please!
EDIT: I'm attempting to install with the latest version of the on-line installer that was just posted today.