I too am having problems with my new Nexus 7 [2013] running Android 6.0.1. I've had it about a week.
I'd like this to be a dedicated Phantom tablet using Litchi exclusively for my P2V.
It lags while loading maps - much slower than my cheap Korean tablet. But that's the least of my problems.
The first few flights I'd lose FPV when it shouldn't, but it would come back. But the Litchi app would also crash periodically. I realized it wasn't in airplane mode and so put it in airplane mode with wifi on. Now when I fly out on a distance run, I'll eventually lose the FPV and telemetry as expected, but when I turn around and get back into range, it won't reconnect. I'll fly it all the way home and land it in front of me and it refuses to reconnect. I have to exit the app and reload it, and then it will connect.
This tablet is loaded with apps - I count 41. Most of them came with the tablet. It also has a bunch of widgets. I will start uninstalling them.
I have some other ideas too, such as going into the setting/wifi app while in flight and trying to force connect on the phantom stream, but this wouldn't be exactly convenient while flying, and I don't even know if it will work.
I am loading the newest update (March 1, 2016) as I am typing this. Maybe that will help.
Any obvious advice, I'd appreciate it. Thanks!