Greetings Recovery 1,
First things first, I'd look at how you're interfacing the TZT3 with the commercial Class A FA170. With this product you can either bring AIS information into the NAVNET network by ethernet or CanBUS vis-à-vis an IF-NMEA2K2 NMEA0183 Serial to NMEA2000 gateway. If you are using a serial converter, make sure the com port and converter is set for AIS mode or NMEA0183-High Speed to accommodate for the high network traffic. If you are using ethernet, check section 3.8.5 in the FA170 Installation manual to make sure [NAVNET] is selected for NW PROTOCOL. If it is, I'd review section 3.6 on making sure your settings look correct for NAVNET protocol.
ref.:
https://furunousa.com/-/media/sites.../public_manuals/fa170_installation_manual.pdf
Hope this helps,
- Maggy