3820R Playback problems happen intermittently on multiple apps

I have two Roku Sticks and a Sharp Roku TV.

     The TV is a Sharp LC-24LB601U and has Roku version 12.5.5 Build 4174-69.

     One stick is a 3800X, with version 12.5.5 Build 4174-55.

     The other stick is a 3820R, with version 12.5.5 Build 4174-E6.

The TV and the 3800X work fine.  The 3820R often, but not always, will not complete the login process on the Max app.  On the Hulu app, it will play live TV fine, will play recordings of live TV fine, but will often not play anything from the streaming library - just gives me the spinning circle of death.  If I put the 3800X on that TV, everything works fine.

I've already done all the standard reboots, re-installs, etc. 

It seems pretty obvious to me that if build 4174-69 and build 4174-55 work fine, but build 4174-E6 has problems, then the problem is either in the build or the device. 

Also, the 3820R (build E6) has another behavior that makes me suspicious.  On both the other devices, when Roku starts up, I get what I call the Roku "dance", where the characters dance around while the device completes booting.  The 3820R doesn't do this.  The "Roku" logo appears for a couple of seconds, then it goes directly to the home screen.  However, it takes three or four times longer to connect than the 3800X from the same location on the same network, and then after it connects, I have to press the cursor control anywhere from three to 10 times before anything moves.