System Alarm Data: Heading Not Available

[Take 3]

I have the Raymarine E90 chartplotter, autopilot, gps, depth sounder, Radar, wind indicators on a seatalk network purchased with my then new 2014 Jeaneau 44DS sailboat. Everything worked fine for 8 years, then a couple of years ago an intermittent problem started occurring where I would lose one function after another every 10 minutes or so. Of course it would not repeat this behaviour when the Raymarine tech was onboard. Unfortunately my entire system is almost unusable when it happens. Yesterday 30 minutes after leaving the dock I started getting System Data Alarm: Heading not available, and No pilot Head. Depth reading also disappears, speed over ground disappears, wind readings go, gps location on chart plotter goes too. I've seen some threads similar, but not quite as bad as this. I replaced the Network hub, but it has made no difference. Anyone out there have any thoughts?