Error:SMTP connect() failed.

I installed the SuiteCRM on my Synology 713+ running DSM 6.1, Appache 2.4, PHP 7.0, Maria DB. I get the error Error:SMTP connect() failed. and don’t know what to do (tried almost everything that passed my mind).

Please advise!

Several people are experiencing this problem, see (for example)

https://suitecrm.com/forum/suitecrm-7-0-discussion/13858-email-settings-error-can-t-figure-out-why#46662