Sounds very much like a network issue of some description is preventing you from being able to connect to an Electrum server properly.
If you are not already using v2.9.3, then you should upgrade:
https://electrum.org/#downloadIf you are on v2.9.3, try going to: "Tools -> Network" and uncheck the "select server automatically" box and then right click on a different server and select "use as server".
You might also want to make sure your firewall and/or antivirus isn't blocking outgoing traffic on the ports that the Electrum servers are using (typically 50002, but a few use 50012 or 51002 etc, you can see on "Tools -> Network -> Server" window)
refer here:
https://bitcoinelectrum.com/how-to-switch-to-a-different-electrum-server/