There is the problem. Versions older than 3.3 are no longer able to connect to Electrum servers. You need to update your client to the newest version. Make sure you do it from the official Electrum site and it is highly recommended that you verify the signatures of the downloaded file.

Also note, version 3.3.4 is the newest one. There is no 4.0 or anything newer than 3.3.4!

EDIT: seems TryNinja was faster and wrote his post while I was writing mine. Damn ninjas