Writing software is hard enough, but writing client-server apps is super-hard because you not only need to think of all the ways a user might misuse the app, but how the bad guys might misuse your server.
I have a friend who's been in the business for decades but he's burning out from having to deal with all the security overhead. It's a much more dangerous online world than it was 20 years ago.
But it's all learnable if you're patient and eager to try new things. It helps if you also enjoy coffee.
What OS is your server running? And is it a shared host or VPS?
PS: Self-learning is the best learning. It's the only learning, really: whatever you learn in school is just a foundation, most interesting professions these days require life-long Self-learning anyway. It's a good habit to build.