Openvpn - no tcp port binding?

[GreenMatter]

I used to have 2 working instances (tcp and udp) of openvpn road warrior setup. UDP has random port and TCP has 443.
Recently I’ve discovered that I can’t connect to TCP server. When I was looking closer at it, I couldn’t see port 443 opened on WAN interface despite of no related to it errors in log.
The only thing what has been changed recently in config was adding gif interface and configuration of Tunnelbroker IPv6 access on couple of vlans.
How to troubleshoot it more precisely and find location of where openvpn binds tcp port?