Hello,
We are also having the same problem with our DLink. We have tried moving the DLink, changing Ethernet cables to the cRio, and using other DLinks from previous years. We even tried using a DLink with only two computers connected to it and nothing else. When we tried to ping one computer from the other, after a minute or so, the ping response would be very slow for a few seconds, then go back to normal. When we did this same ping test while the cRio was connected, the slow ping response corresponded to the hiccups on the robot. The hiccups will happen anywhere from a minute apart to 5 minutes apart. I have attached links to some images from the Driver Station log viewer that shows the hiccups happening. the blue spikes on the graph show packet loss.
Ping test image with the computers
Driver Station Log
Zoomed in hiccup on Log Viewer