Server starting then stopping

Hi. So, whenever I load my server up, I log on and it works normally, I can place blocks, type commands and chat. Then after about 15 seconds, the server stops and I get kicked with a "Timed Out." message. I've deleted a ton of plugins in case that's the problem. Doesn't work. I don't have any modpacks installed.

The Timed Out message may just be my connection, but the server still stops after being up for only a few seconds.

No, it's not that. The server stops after 5 minutes of not being played. Not 15 seconds. And it usually only stops once I've clearly logged in and it recognizes me being on.