Symptoms
You use a VPN to connect your mobile device, for example your laptop, to your server. All traffic should go through this VPN, as you do not trust random networks you may connect to. This works fine, except when you try to connect to your server through its public IP address. As this is also the IP address that is used as the VPN end point, traffic to it does not go through the VPN but is routed, unencrypted, through the untrusted network.