Typical problems with the VPNOpenVPN setup:

* You cannot It's not possible VPN into your network from your very own network . This is not possible and it will fail (kinda duh)* You cannot login two users simultaneously. The OpenVPN setup is single-user.* You cannot login to your network from another network with the exact same settings. This is not possible due to routing. You can probably reach your own HDA, but not other systems in the network, due to routing (the HDA has direct connection via the VPN tunnel).* Check that you have port forwarded 1194 udpUDP.