I've been having problems with my Ethernet switch connecting to my graphs. It probably only connects 30% of the time I'm on the water. Lately when it does connect, my shared screens are black. I sent the switch in for repair last week. So yesterday I connected my bow graph, helix 9 di chirp g2n to my main council graph, helix 9 mega si g2n. The shared si screen on bow graph was still black. What could I do to fix this problem?