The server is currently removing blocks from that world that no longer exist, and this process can take quite a while. Until it finishes, the server will be unreachable. This is due to the ChickenChunks removal and the Galacticraft update. That said, we just pushed another client update. Please update again. Thanks! Update: Server is up.
For anyone who's interested in a replacement for the Chickenchunks chunk loaders, and hasn't been told/isn't aware, there is an alternative. Personal anchors cover and load a 3x3 chunk area, centered on the anchor, and they no longer require ender pearls to be fed to them as fuel, and their materials cost is comparable to a chunk loader, though this recipe requires emeralds, which may be harder to come by given your individual situation. If you're in dire straits to have them, and you've lost chunk/spot loaders in the update, you can ask a mod to comp you some personal anchors as compensation for lost materials. You'll know they've loaded the chunks when the pearl icon on top goes from red to green. Just an FYI in case you didn't know.