I don't think your problem is with HDMI or HDCP. As the user you quoted says, the app queries the hardware for those, and simply refuses to play the higher resolution if the standards are not met. The problem is most likely with your internet connection.

I'm getting similar stutter on an older 1080p tv. I thought it was the box, but I get smooth playback hooked up to a new monitor. A fix would be great!

I've had horrible issues with my Mi Box (netflix, hbogo, etc) on an early gen 1080p LCD, which is connected through an AV receiver. I often wondered if it had to do HDMI / HDCP support or lack thereof. I never tested it with a newer TV though.

This may not help much, but try to go into settings and change your display resolution. I have a small 720p tv, but its set to 1080p, no problems. When I changed it through different options, I noticed there was choppiness in videos. One was really bad (I think 1080p at 24Hz).

I'm interested in buying a Mi Box but am hesitant due to all the reports of dropping frames.

I had an old WDTV Live Streaming box which had problems with this, on an old 1080 portable TV in my bedroom. Out of desperation I tried altering every setting, and realised the issue was with CEC.

https://en.m.wikipedia.org/wiki/Consumer_Electronics_Control

Why this would make any difference, I don't know... Maybe it was continuously trying to adjust to the "correct" display of the TV, instead of using my chosen settings? It seems that CEC checks for "system configuration"...

Once I disabled CEC in the WDTV settings it was fine. Is there a "CEC Off" option in the Mi Box's settings???

After googling, it appears most TVs will have an option to disable CEC:

https://www.google.co.uk/amp/www.howtogeek.com/207186/how-to-enable-hdmi-cec-on-your-tv-and-why-you-should/amp/

Could anybody having problems try turning-off CEC and report back?

Sounds more like an internet issue. Interference maybe, or weak signal, or congestion. If not already hardwired and you can't find or fix the above possible issues than maybe try to hardwire it (USB ethernet dongle should work if you have a mi box)

I am no expert, but that statement seems wrong. If it's a 1080p TV, then it shouldnt get only SD quality from its HDMI 1 inputs. It would be a horrible marketing bait and switch. Ie, the screen is HD but it's impossible to see HD because we only put standard def inputs on it.

As long as Netflix can send out HD signal through the user's internet, the HDMI sends it through as is (unless there is a problem with the wire or connection). That said, your problem probably isn't the wire/wire connection. If it was then you would be picture issues (no picture and sound, poor quality picture, flickering, etc), not the hiccups you're experiencing.

Summary: probably your wifi.

Interference:

Try to move away cordless phones, laptops, anything wireless. Also if you have 2 bands (2.4GHz and 5GHz), try switching bands.

Congestion: Try not to be on a ton of devices at once, if you are. Downloading from one computer, YouTube on another, websurfing on another. Do too much on one network can slow things down.

Weak Signal: There should be an indicator of Wifi strength on the device. I don't know where off hand though, sorry. If it's weak, maybe try a wifi bridge/extender. Or if possible get your router closer to your device. USB ethernet dongle might be easier and cheaper provided you don't mind getting a ethernet cable from your router to your device.