Server Options

My server works perfectly now, but for some reason the options (like monster disable and difficulty) don't save. I try turning PVP off and it works once or twice but then after that it says it's off in the options even if I refresh the page it still says PVP is off but when I start the server it's on. Is this a problem with website or server? We run a vanilla server so we can't configure things in essentials because we try to keep it vanilla but sometimes the difficulty changes from normal to peaceful and we wouldn't know until we start the server.