Crash server

The server keeps crashing out of nowhere without me doing anything in between :( The server is crossplay, and the first crash happened when a Bedrock player joined, then the second one happened when two Java players were playing normally. Server type: crossplay, version 1.21.11, created a few hours ago. I've been wanting to try the free version of the server so I can host it here soon, but I don't know why these problems are happening :,)