This 15x-release is troubled.
For the first time since using John's fork on my AC56U I had to go back a release. I've tried 15E3 and 15E5, and with both, my Android devices (Galaxy Note 3, Moto X Play, Xperia Z Ultra) tended to drop connection sometimes during their standby. They are on 5 GHz, on 2.4 I have no permanently connected devices going into a standby (the Chromecast stick never does). Now back on 14E1, the connections are solid again.
Edit: no resets were made, Regulation Mode is off, regional limits are off with "#a/0", 5 GHz set to 200 mW.