Q: OS X Caching Server and iOS App Store regions

I live in Turkey but I use the UK App Store for my iOS devices, Macs and Apple TV. This has always worked flawlessly, fortunately Apple have never implemented any georestrictions, I hope it stays that way.

Anyway, I recently setup a caching server on a Mac Mini, latest version of OS X Server running on El Capitan. In particular i was hoping that iOS devices would benefit from this, as we have quite a few in the house now often running the same apps.

However, I have found that this only seems seems to cache OS X software updates and iCloud data. It does not cache iOS downloads or updates. Nothing appears in the server caching log to indicate an attempt by the caching server to service the requests.

As an experiment, I switched to the Turkish iOS App Store and found that caching worked fine for downloads and updates for this store. This shows that there is nothing wrong with my network, I.e. the OS X Server and iOS devices are using the same public IP address and can see each other across my LAN.

So I'm guessing there is either some kind of regional aspect built into it the caching system or this is a bug. I don't understand why the Caching Server can't download the iOS software from the UK store just like the iOS devices can do directly?

It seems I need a way of having the Caching Server be set to "point" to the UK store despite having a Turkish IP address but the process seems automatic and based purely on the public IP address. I considered and indeed experimented with a VPN on my router with partial success. Entries began to appear in the caching server log but I still couldn't get it to actually cache and re-use items, though I didn't troubleshoot it very far because it wouldn't be an optimum solution anyway running everything through a UK VPN purely for this.

Does anyone have any suggestions as to how else to work around this issue? It seems the caching server could do with an App Store "country" setting rather than rely on the public IP address to determine location. Certainly it doesn't use whatever region the App Store on the Mac is set to use.

To verify my findings I also tried setting up the Caching server on another clean Mac Mini install but achieved identical results.