How do I learn

…you say in your OP. Yet instead of learning, you complain “what kind of crap server is that”. You don’t learn by thinking anything is the softwares fault.

It is perfectly normal, that you can reach the server IN your home network only when you are connected TO your home network. That is a security feature by your router and thus by design. But in order to learn how to open it up, you would need to be willing to learn. About security, about networking, about how to find servers, i.e. the internet and more.

But for the beginning: how is that even bad or crap? Like, it saves your photos when you come home and connect to wifi. Awesome, congrats!