I would love to see your code including the web api? Are you using signalR to update your page?
Its quite easy into interface ND's to MVC/WebAPI the biggest problem is keeping the data you send and receive very terse to the ND so as to minimise the amount of string operations that need to be done on the ND. in the past i have done things like hard code the action names as constants on the nd, then using a RESTful API sent the bare minimum of data to and from the ND.
One trick i used to minimise data being sent over the wire was to use the ND's MAC address as its unique identifer so i could target any given ND on the network.
I also keep meaning to have another crack at writing a SignalR client for NetMf (there is the start of one in the SignalR repo on GitHub).