Hi,
I have experience working with openVPN in particular with Linux distribution like IpCop, SmoothWall, Endian, and openBSD PfSense, however the function is very similiar for each. I also know to use wireshark but maybe with other simple tools can help to verify the problem like a traceroute, ping, redirect ports, and port testing with external web.
It's important to know if the conections are for client vpn or if you are making a site to site tunnel.
I hope can help you.
Regards.