I installed a Nmea4Wifi multiplexer 3 years ago to be able to get AIS informations in my navigation softwares.
Installation was very simple.
I cabled via NMEA the on-board GPS to my VHF radio which has ASN and AIS functions.
The NMEA output of the VHF radio was cabled to the Nmea4Wifi input to be able to get both GPS and AIS informations on my smarphone and the tablet. +12V was connected to navigation instruments power source in the boat electrical panel.
I am using it both with Navionics Boating and OpenCPN software without any problem.
This multiplexer is very stable and it consumes few power (much less than my old on-board GPS/plotting device
).I intended to use also SeaTalk input to get wind and speed over Ground but my old ST instruments went out of service before.