Radicale.org is a free Python based calendar service that you can use to host a calender using the caldav protocol. It normally uses port 5232.
I have been trying to set up this software lately and have been running into an issue.
When I host the software on a local machine on my own network, everything works fine and connects. The plan is to host the software on an external machine on another network and contact it through its IP and port where the calendars will be hosted.
The issue is, is that everything I try to connect to it ultimatly fails. Telnetting through to the host IP in combination with 5232 yields a timeout issue. Generating a calendar in Lightning also doesnt work and also yields an error. Timeout error 504.
According to one of my colleagues, port 5232 is in fact open as the external machines router has it open and the port is enabled in the firewall as well.