Own APN config. with Proxy Settings - No Connection

Hey everybody,

we've a strange Problem in our company environment. We are using a custom APN with no direct Internet Access. For Internet Access we configured a Proxy Server in our APN Settings.

Now we would like to gain Remote Controll on our Device - but unfortunately we do not get an ID or anything else.

in the Logs it says that we timed out.

There is no Proxy query like with the Windows Client.

Our Proxy is a Sophos UTM in Transparency Mode.

Device are Samsung SmartPhones with latest Android and MobileIron as MDM.

Thanks in advanced for any Tip you got

Greetings

Chris