Finally after two hours trying one transaction was accepted at server electrum.no-ip.org
I use TOR to connect, could that be the reason?
When using TOR you need to specify the correct port in order for you not having problems with the servers. For TOR itself the port is 9050 while for TOR BROWSER BUNDLE (which the majority of the users use) the port number is 9150 . Once these ports are correctly configured you will never have problems using Electrum via TOR.
Go to Wallet/Network/Socks5 then under proxy enter the IP 127.0.0.1 and port 9150 (since I am assuming you use Tor Browser Bundle)
Restart Electrum wallet in order for settings to take effect.
I already had these settings set correctly Wallet/Network/Socks5 then under proxy enter the IP 127.0.0.1 and port 9150
The problem is happening today again. It is highly annoying. I have to wait for hours until I can send a transaction, I get the server did not respond message all the time.