I've had the same problem with Amazon prime in the past few weeks, some of the selection that is available plays OK and some comes up with insufficient bandwidth when using my Sony Blu-Ray/smart box to the TV hard wired to the SHub in router mode, previous to that everything worked OK, although when checking, all the content selected plays OK on the PC. Several broken up phone connections to Indian support doesn't help either. I'm not sure if the fault is with Virgin's or Amazon's prime bandwidth or the SHub's allocation. All the connections in the SHub3's panel are reading at 1000Mb although the aux device is showing as unknown in the SHub3. and my TV is HD not 4k
Update: seems now to be sorted. I disconnected the RJ45 cat5e cable from the hub and the smart box and then tried the Internet and Amazon prime with the smart box it then asked for the cable to be connected after which it gave me a code on the TV screen to put into http://Amazon.co.uk/mytv
after which it then created a new device connection and that seems to have sorted it out, at least for now, touch wood.