(DG) N with a square around it

[shay]

I have recently installed two Raymarine eS series MFDs. My system includes a Vesper Vision AIS that is connected to my lower eS 127 via NMEA 183. The AIS functions and displays properly. Almost every time I use this system, I have a problem where I get a square with N in the middle. There is a line connecting the box to the boat symbol, as if it is a vector. When this happens, I can no longer activate or exercise a route. The only way I have found to get rid of the box is to shut down the eS 127. I have spent hours searching thru the manual and can't find a reference to this symbol. Can you tell me what the symbol means? How I should get rid of it? And how I can keep from having this problem in the future?