For one you are using a really old, outdated version of osTicket and you need to upgrade to either v1.14.7 or v18.104.22.168 and retest. Also, if you're having to restart the server to get osTicket to work I don't think this issue would be on the osTicket side, rather the server itself. It would be helpful for you to check all the stats (CPU usage, RAM usage, available storage, etc.) and logs (general server logs, PHP logs, MySQL logs, etc.) on the server to see if there is an underlying issue somewhere.