Safari on iPad Air on iOS 8.1.3 can't open SharePoint 2013 (windows auth) site on cellular network

We're experiencing an issue with all iPads on iOS 8.1.3 on all cellular providers (tested on AT&T and T-Mobile) that when opening a SharePoint 2013 Farm (SP1 and Dec CU) which uses Windows Authentication, we get an infinte loop of authentication prompts. We've confirmed that on the same devices the experience works fine when accessing the farm using WiFi (even if it's through an AT&T Hotspot for example). Any thoughts on why would this not work when using cellular data but works fine on WiFi? Also this only happens on Safari, Chrome works fine.