It must be a problem with your internet connection - or something else is installed that interrupts the download. Remember, you had that before, where your family blocked various sites. ;P
When you see a loading screen with bar, you can click into the black and hit your "F12" key - that will show you a detailed progress. Even with that, though, if the files don't download more quickly, the game can't do much about that.
If you get disconnected during the loading screen, then something messed with your connection to the game server. There is no "time limit" for loading; the game server and client do send each other signals to indicate they're still there, but they also work while on the loading screen.
The hourglasses indicate a problem with your connection as well - if you see an hourglass as an item, then the game client is still waiting for that item to be downloaded. These files are really small - like 3-4 KB. A normal download. If you see an hourglass longer than a few seconds, then that might be your connection too. If downloading a 3 KB file takes long enough to download for you to notice the hourglass, I can imagine how loading a new map would be slow. You can enable or disable SSL and see if that makes a difference again.
From my point of view, people can connect and play just fine, so this is likely on your end.
My advice from my last post still stands; we've shown that there's
software on your computer messing with your connection. Hence, I would consider the computer compromised. The only definite remedy is to do a full backup, wipe it clean, and restore just the files that you need and know to be safe.
(Also, the mines are indeed a dungeon.)