The latest firmware(v3.6.4) for DrayTek Vigor 2850 line of routers breaks Anywhere Access for Windows Server 2012 Essentials when it is setup with an Static IP address and an SLL Certificate for your own domain name.
The problem lies to the new feature introduced by DrayTek latest firmware called SSL VPN. This feature by default uses port 443 for any SSL VPN connections which in turns bypass the configuration of Windows Server 2012 Essentials for port redirection of https requests to be delivered to RWA Website.
The DrayTek’s Support answer which fixes the problem:
1. go to SSL VPN>>General Setup, and change the port from 443 to another one
2. go to System Maintenance>>Management, and change the HTTPS Port from 443 to another one.