Connection timed out (110) for test email

Hey, I’m getting a

Connection: opening to smtp.gmail.com:587, timeout=300, options=array ()
SMTP ERROR: Failed to connect to server: Connection timed out (110)
SMTP connect() failed.

error sending the test email

Server info:

OS: Linux sn7.zone.eu 3.16.38-1 #1 SMP Fri Oct 21 20:55:52 EEST 2016 x86_64
PHP version: 5.4.45
WordPress version: 4.6.1
WordPress multisite: No
openssl: Available
allow_url_fopen: Enabled
stream_socket_client: Available
fsockopen: Available

if anybody has any ideas where the error may be?
The General page SMTP status is OK