The firewall sits between OS X and the internet and only allows incoming traffic to come through on specific ports. OS X manages the firewall on a per-application basis, but sometimes you want to

x.x.x.0 255.255.255.0 (my private network) private 0.0.0.0 0.0.0.0 public. NB: My ISP is NOT blocking any ports. I am aware of the "advanced" guide provided by Apple. I have been able to access the server when inside my network (-_-) Trying to connect from 3G network with iPhone 4 gives "L2TP VPN server … TCP and UDP ports used by Apple software products Aug 27, 2019 Port 1723 (tcp/udp) :: SpeedGuide

Once connected you can go to IPLocation.net to check on your new vpn secured IP address. To disconnect your Mac OS X client from our OpenVPN server, just click on the the Tunnelblick icon and select Disconnect.

There are now complete, working ports of all macOS services in MacPorts, including a much-improved Mail server and Apple’s Calendar and Contacts server. Both the Mail server and the Calendar and Contacts Server also have working APNS if you keep around a method to have a deprecated Server.app version reissue the APNS certificates. Forwarding VPN ports sounds technical and intimidating, but anyone can get the hang of it with the right guidance. Today, we offer a concise overview of what port forwarding is and why you’d want to do it. We also recommend the top VPN providers that make port forwarding simple to accomplish.

VPN Server Configuration is a $9 purchase, so for OS X 10.8 users it may be worth some conveniences over Apple's $20 OS X Server package, but will likely be very beneficial to those wishing to set

Easy to set up. Easy to manage. Easily create, manage and maintain virtual private networks from anywhere with LogMeIn Hamachi, a hosted VPN service, that extends secure LAN-like network connectivity to mobile users and distributed teams on-demand over the web.