Nether "Connection Reset" when trying to enter.

1. What OS are you using (Brand and version - Ex. Windows XP SP3)? Ubuntu 10.04 LTS
2. What architecture is the OS you are running (x64 or x86)? 64-BIT
3. What version and architecture is your java install?
java version "1.6.0_20"
OpenJDK Runtime Environment (IcedTea6 1.9.9) (6b20-1.9.9-0ubuntu1~10.04.2)
OpenJDK 64-Bit Server VM (build 19.0-b09, mixed mode)
4. Are you running any wrappers? McMyAdmin, mcadmin, Hamachi, etc? None
5. What build of CraftBukkit are you running? 1185
6. What command are you using to run your CraftBukkit server?

Code:

java -server -Xms5G -Xmx6G -XX:PermSize=128m -XX:MaxPermSize=256m -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSParallelRemarkEnabled -XX:ParallelGCThreads=3 -XX:MaxGCPauseMillis=50 -XX:+UseAdaptiveGCBoundary -XX:-UseGCOverheadLimit -XX:+UseBiasedLocking -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:MaxTenuringThreshold=15 -Xnoclassgc -XX:UseSSE=3 -XX:+UseLargePages -XX:+UseFastAccessorMethods -XX:+UseStringCache -XX:+OptimizeStringConcat -XX:+AggressiveOpts -jar bukkit.jar nogui

7. What error are you getting (post your server.log file)? There are no errors regarding the nether plugins that I've tried, or the world in general. I've tried three plugins, uNether, Nethrar, and one other that I forgot the name for.
8. What have you tried already? I've looked through error logs, changed plugins, switched server.properties nether option from false to true and the opposite for each plugin.
9. Have you tried any of the things below? Yes, I've tried them all.

ADDITIONAL INFORMATION
Players are able to go into the nether, but it disconnects them after about half a second to a second. It says "Connection Reset", they are able to log back on, then it kicks them again and again. No errors, just the annoying "Connection Reset: xxx.xxx.xxx.xxx" in console. No clue what's happening!

I can run a nether world fine that I've generated, and make a single portal with AncientGates fine, nothing is wrong there, the world works completely fine. But it's the nether portals in general that are made by user or by a nether-based plugin that crash.


Anyone have a clue?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

I actually was getting this the other day while testing the new version of Nethrar, and then it magically went away. I honestly have no clue what was causing it :/

Actually, I might have a clue what is causing it... let me make a custom build of Nethrar later tonight for you and see if that solves your issue. I'll also check out AncientGates to see if they're doing what I think they are doing.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Ive been having the same issue and no matter what plugin I use to get to the nether me and my users just get booted after a few secs and I usually have to reset the player to spawn. Using 1337 multiverse, wormholextreme and many other plugins