Forge version:
Twilight Forest version: (1.12.2-3.6.345)
Link to crash log: (https://gist.github.com/Bofumofu/423f192dc45912e6c72851afd44a0834)

Steps to reproduce:

1. Run a forge-1.12.2-14.23.5.2768-universal server
2. Create a functioning portal.
   3.Go into the portal

What I expected to happen:
Enter the new dimension

What happened instead:
Server crashed, everybody timed out , when I restarted the server I was in the new Dimension and I even could get out of the dimension by recreating a portal there.

The log provided does not appear to indicate any crashes, despite the server allegedly crashing (unless Time Out means crash). Do you have a crash log of this event, if there is one?

On another note, your mod is outdated, and the issue may be no longer present. Can you update it?

everybody timing out could mean that your server was just having difficulty handling the new dimension being loaded/created. did your server software actually close, or just everybody timed out? @Bofumofu

edit: your server logs suggest this is the case, last line is it saying it's having trouble keeping up lol.

[18:42:33] [Server thread/WARN] [net.minecraft.server.MinecraftServer]: Can't keep up! Did the system time change, or is the server overloaded? Running 2166ms behind, skipping 43 tick(s)