Nitrokey Pro OVER ETHERNET / IP (Windows)

Has anyone tried connecting a Nitrokey to a machine remotely?

I have tried the following 3 products on Windows 2008 and 2012 remote servers:

All 3 successfully connect the Nitrokey to a remote server. The Nitrokey app on the remote server shows the key is connected and I am able change the PIN. However, the key does not seem usable.

GPG does not see the card.
OpenSC show no readers were found.

The only test where it was successful was with a key plugged into an AnywhereUSB hub. I was able to use the key with a Windows7 machine (that previously had the same nitrokey pro plugged into it).

Could it be I need to manually install extra drivers or something to get it working on the remote servers?
Or is there something built into the security of the NItrokey Pro that stops it being used this way?

The Nitrokey is not aware of the USB-over-Ethernet setup. In case OpenSC or GnuPG recognize the device when executed as root, it may be an access rights issue. Do other USB devices (e.g. an ordinary USB drive) work well over Ethernet?