This has been happening to a lot of people, and seems to be connected to the amount of people on a map at one time. Fluorite, as we all know, is the most populated map, and therefore it seems that for many users, once the amount of people on the sever gets to a certain point the game for some reason overloads or stops working and therefore shuts itself down.
Unfortunatly, as for the solution, I've found that the best is just to wait. Try a character maybe on a less populated map (South Pole, for example) and wait a little bit for the map to calm down. A good thing to do is check the side bar on here that has the maps and the number of people on it. Many people get booted at teh same time, and you'll see the number of people go down. Once the number goes back up, try to get back on then. I'm not sure why this has started happening (I know next to nothing about servers) but it seems all we can do is wait and be patient.
Btw, I'm not claiming to be an expert on this subject, and it may be that I'm totally wrong and a senior user who knows much more than I do comes on with a totally different explantation. But this is what I've gotten through my observations and frusteration with the same problem.