What ports for apps hosted in the Google Play Store?

Hi,

I am using MEM Intune, Corporate Owned Dedicated Devices (CODD) for Android, and I'm noticing that on some sites when the Android tablets are enrolled, they get stuck at the point of downloading the apps.

The apps are being hosted on the private Google Play Store, and where tablets are enrolled from my office location there are no issues, but like I say, at my customer sites they are not downloading the apps.

I'm wondering if it's a firewall issue.  Does anyone know what ports need to be open for this?  I have googled, but can't find a good answer.  I have checked that they have 80 and 443 outbound open.