hi, i have this problem too...
i have 20 machines and only 6 stays ONLINE on Portal all the time....
i use pfsense firewall. when i dont use it, works fine.
but i need my proxy/firewall server...
looking my cfg file:
[bc]
base = bcons-core.ff.avast.com:80
registrator = http://{}/register
handler = http://{}/handle
install_id = d2696
my firewalls runs in transparent mode (192.168.1.254:3128)
any sugestions?