Help! "Connection timed out" - Zoho Mail Android App

Help! "Connection timed out" - Zoho Mail Android App

Hi,
I'm having a lot of connection issues on my Zoho Mail Android App lately, if I'm using a 3G connection.

It keeps showing the "connection timed out" message (as you can see in the image attached) whenever I try to get new emails. It's definitely not a internet connection problem, because I can browse the web and get my corporate mails using another email app at the same time, with no troubles.

The weird thing is: If I connect to a WIFI connection, it works like a charm, and I can get my emails.

Could you please help me with this problem?

Regards,
Carlos