27.02.2017 05:38:32.000 1488191912 (null) Error:Cannot connect to unknown (unknown:80).
27.02.2017 05:38:32.000 1488191912 (null) Return code: 0x20000004 [Cannot connect to unknown (unknown:80).]
27.02.2017 05:38:32.000 1488191912 (null) Stopped: 27.02.2017, 05:38:32
These lines suggest that the mirror server is trying to download the updates through a Proxy server.
Open AEA > File > Settings > Mirror Proxy and make sure to select "Direct connection (no proxy)".
Then attempt to download the mirror updates by running "C:\Program Files\AVAST Software\Enterprise Administration\mirror\mirror.exe".
If you receive the same error, please run the below commands in CMD with elevated access and let us know what is the result:
netsh
winhttp
show proxy
If iirc 0x0000274D is a postgreSQL error.
The hex 0x0000274D converts to the decimal 10061 which is a standard windows net error code and it means: "No connection could be made because the target machine actively refused it".
You can find the error meanings by running the following in CMD: net helpmsg ERROR_NUM e.g. net helpmsg 10061