Office branch Client should connect to Era server through proxy. You can acces it (look on reports, alerts, send policies, send installation tasks etc.) by ERA6 www site.
But first, Client agent should have configuration to connect proxy on 2222 port, and proxy should have config to connect server on 2222. They all should have appropriate certificates ( for agent, proxy, CA), and open 2222 port on firewalls, if you use fqdn names don't forget to configure DNS