There are a number of ways to allow users to use P4 Plan remotely from home or outside of your local network. The easiest way is to allow users to connect to the server directly over the Internet. All communication after the syncing process is finished is handled with 128-bit AES encryption with a key created from the users password. To allow users to connect to the server over the Internet you need to forward the server port to the P4 Plan Server machine. The default port is 50256 and can be configured in the Server Administrator.
If you want more secure communication you could let the user connect over a VPN connection.
It is also possible to run the P4 Plan Client in a Terminal Server environment. Performance will not be optimal and it is recommended to allow users to connect directly to the server instead.