HttpWebRequest Timeouts, only on Android Tablets

I'm running Xamarin 4.0.12(3) and MonoDroid 4.8.1.

It seems HttpWebRequest is unstable. I've seen plenty of posts on past versions but nothing saying there was an issue with 4.8.1. My code works fine on phones (GS3/Droid2) etc but when I try run it on a Nexus 7 tablet (running v4, JB) I just get a timeout making any HttpWebRequests. My target android version is 4.

Any thoughts on how to debug this further? Do I need to open a ticket?

Thanks