I recently started new mc server spigot with plugins. It worked fine. But after 100+ connections, 10 multiverse (plugin) worlds, and milion blocks i restarted the server. All was fine, spigot console commands worked (from SSH) but when i connect to server from pc, server immediantly stoped responding, from virtual box (not via SSH) console and i wasnt able to write something or just log in. After ubuntu server 18.10 restart from virtual box server was responding. But when i ran the spigot server from byobu, and connect from pc, ubuntu stopped responding and i haved to restart server again.
Sorry for bad english :v
(Using ubuntu server 4GB ram, 4 cores ver. 18.10, java: openjdk-8-jdk (package name))