New to Fortigate Webfiltering, Enable Webfiltering but keeping Microsoft Exchange mailbox

Good Afternoon

I am fairly new to Advanced Fortigate settings like Web-filtering and SSL etc

I am Trying to Enable web-filtering for my company moving over from Sophos to Fortigate recently.

I would like to start restricting the network of Facebook, YouTube, Porn sites etc,

but if I enable the Policy then my exchange mailboxes goes offline and give SSL error son all my computers.

Another thing I am looking at is separating my mobile devices from my computers on the same network, as my phones connect on my Unifi-Wireless System and my laptops do the same. Is there a way to safely separate them so i can start restricting the cellphones internet usage as well?

Kind regards in advance