First of all when you want to add a new UpNp device, this device and a media server must be switched on otherwise the remote will not find them. Unfortunately the remote will only find a media adapter if it answers over the network to the remote with a special UpNp command. This is not always implemented in the media adapter. For example:
The sl400i/sl300i philips streamium devices do this (they are designed to cooperate with the remote), but
the slm5500 or the sla5520 also philips streamium (but developed by different company the the above) are not doing this and they don't show up in the screen. Since the next button is then greyed out you will not be able to add such a device as UpNp media adapter.
This "bug" or whatever it is has been reported (by me and several others) a long time ago, but it is never resolved and it will never be resolved I'm afraid.
You can add the Netgear as a htpc and program every button manually so you will be able to control the basics, but you end up with an activity including a record button and a tv guide, while this is not necessary for the netgear.
Just a side note: are you able to connect with your remote to server by the 9800i activity?