At the risk of sounding naive, can you use a router and a WiFi tv and a laptop with WiFi but no carrier?
We like Plex because it is easy to say find a comedy to watch on our USB drive because it catalogs all the content. However we rarely have a WiFi signal good enough to stream especially at anchor.
yes yes. You have an internal wifi network on the boat and your devices -- ipad, tv, laptop, etc. -- use it to access your NAS, where your movies, tv shows, ebooks, and other stuff is stored. In those rare cases where there is access to an external wi-fi (marina wi-fi?) that is connected to the internet, you set your internal wi-fi to bridge mode and use it. You can also tether your phone into your internal network and use that for an internet connection, though this is not a straightforward process since cell phone companies hate it.