If you are having crash issues, try this.

[RpTheHotrod]

My server was fine for awhile but started getting errors here and there and it ultimately led to constant crashing. After disabling ALL of my plugins, I STILL had issues, so it had to be a mod.

I rolled back my server and disabled both Better Dungeons AND Dimensional doors. Ever since, no more freezes, no more errors in console, and zero crashes. See if this works for you.

[likegames]

But Better Dungeons is a key part of Hexxit :(

[ubur]

You will stabilise it quite a bit by disabling ships in better dungeons though you will still have issues with underground dungeons. These issues were fixed awhile ago in BD, but Hexxit doesn't seem to want to update it.

If its a private server you may want to update BD yourself, just know that no one else will be able to connect with it without first updating theirs too.