Server doesnt' start

Hi, I've been having trouble connecting to my server, I click on start and it just shows error 504, then it gets stuck on loading for a long time without doing anything else, also I can't seem to access the files, worlds nor backup tabs, they all just take a long time to load and when it finally loads it just shows a white page. It seemed to work for a while, the loading stopped and it showed the start button again and i could access the aforementioned tabs that didn't load, then I tried to start the server again and back to the same problem.