If you want to SSH to a VPS which is running openVPN do the following:
source: https://serverfault.com/questions/659955/allowing-ssh-on-a-server-with-an-active-openvpn-client
The problem is that the default gateway gets changed by OpenVPN, and that breaks your current SSH connection unless you set up appropriate routes before you start OpenVPN.
What follows works for me. It uses iptables and ip (iproute2). Below, it is assumed that the default gateway interface before OpenVPN is started is "eth0". The idea is to ensure that when a connection to eth0 is made, even if eth0 is not the default gateway interface anymore, response packets for the connection go back on eth0 again.
You could use the same number for the connection mark, firewall mark and routing table. I used distinct numbers to make the diffences between them more apparent.