The server spec is an old PC of mine:
CPU: AMD FX-8350 Eight-Core Processor
RAM: 16GB
Storage: 250GB Samsung SSD
Host OS: Ubuntu 16.04.3 LTS
Container OS: Ubuntu 14.04.3 LTS
Doubt that this machine is the problem, since it runs other game servers (7 days to die, Minecraft, etc) as well as Webservers (Nginx, NodeJS, PHP), Databases (Redis, MySQL, Elasticsearch) and other applications perfectly. It's just the avorion server that gives strange behaviour.