I have just pasted the support ticket info..
Thank you for contacting SiteGround Support!
We have an elaborate server protection system that is probably blocking your outgoing requests. Here is a link with further information:
Please contact WPMU and ask them what IP address and on what port your website is trying to make outgoing connections to, so we can allow them.
I need this info for the for a few sites, would it be the same for all?