HTTPS works only under my WIFI

I've a very weird problem with https.

I installed a new ssl certificate on my subdomain beta.gosherpy.com and when I try to access from any device here in my office using this wifi http://ift.tt/1UNj7Iz works perfectly. As soon as I use mobile 3G or another wifi the response is "cannot connect to the server".

I talked to GOdaddy Customer care and they bring me to sslshopper and sslchecker tool which states that everything is good and correct.

I've no idea why under my wifi works outside not. any idea ?

Best