HiFarGone

Is it private home server or a rented one? Whenever you see a "cannot resolve hostname" error, it means that it cannot find the IP address associated with that name. Did you try connecting to the straight IP address and not the name?

I nuked both DIM 1 folders and didn't have problems wIth either mod afterwards...

How are all of the devices connected to the network? I sometimes have something similar when I use my laptop wirelessly instead of a wired connection on my gaming pc. Can you just connect one person at a time to the server and see if the issue still persists?

I would drop a dimensional anchor near the pump. It could possibly be a chunk loading/unloading issue...

Is the MinY value always 1? Will this allow spawning of more valuable resources at higher elevations in the world? I uninstalled my previous version of tekkit and wasn't able to compare it to an older version of the configuration file...