If your openvpn server is virtualized on a ESXi host you may run into a peculiar malfunction:
the vpn will work perfectly except the for the inability to ping the ESXi host and use the vSphere Client from the vpn on ESXi host.
You can do two things.
Check Configuration -> Networking -> Select the Management Network -> Properties
Then Security and check that you have flagged as accepted the policy Promiscuous Mode, MAC Address Changes and Forged Transmits.
Yes, this is yet documented.
But you can do another control.
In IP Settings Check the VMkernel Default Gateway:
if it is not the correct one he could be the bad guy in this story.