what you can do is directing the client manually to the ADNM server instead of relying on the settings set in the communication…
open a dosprompt and browse to the avast installation directory
(something like: c:\program files\Avast…)
aswchams.exe xxx.xxx.xxx.xxx (ip address of the AMS server)…
do a manual update from the client and it will show you which server it used to update.