The max tick rate on your server will decide how long a tick can take until the server shuts down. If you uncap this, the server will no longer shut down after a long tick. By default, if a tick takes one minute, the server will shut down. This can be problematic on heavily modded servers as mods can affect how long a tick takes. Here's how to uncap it for increased stability.
1. Open the File Manager
2. Navigate to /minecraft/
3. Right click server.properties
and click Edit
4. Find the line that says max-tick-time
5. Change the value to -1
6. Restart the server.