1) Download / buy DeUHD. I know, I know, but here's the deal: love it or hate it, until Mike finishes the MakeMKV update that'll do the job, DeUHD pretty much the only option for decrypting AACS 2.1 discs, and even that program doesn't work well on its own. You're still gonna need to use MakeMKV to get a good result.
2) Install DeUHD. IMPORTANT: During installation, select NOT to install the DeUHD driver. Repeat: do NOT install the DeUHD driver.
3) With DeUHD open / activated, insert an AACS 2.1 disc into your UHD-friendly drive. DeUHD will recognize and decrypt the disc.
4) Once DeUHD has decrypted the disc, select "Rip to Disc" and save the disc to your hard drive. And now, go make a sandwich or something, because this is gonna take a while.
![Smile :)](./images/smilies/icon_smile.gif)
5) Once the "Rip to Disc" process is complete, follow these steps to save your movie in an MKV container:
a) Open MakeMKV
b) Select "Open File"
c) Navigate to & open the movie's BDMV folder (if you saved this to default, it'll be at Users>YourUserName>Documents>DeUHD>MOVIETITLE>BDMV)
d) Select and open the file index.bdmv
6) MakeMKV will successfully open the (now decrypted) AACS 2.1 disc, but it will also detected that you're using an external program. If MakeMKV prompts you to close DeUHD, do NOT do it. Ignore this warning & follow the directions to make your .mkv as normal.
I can 100% confirm that this method absolutely WILL allow you to decrypt all three current AACS 2.1 discs (Fury, Patriot and Stand by Me); that the resulting .mkv files are, in fact, 4K HDR resolution with relevant HD sound (I think Dolby Atmos); and that no errors are generated (at least none were for me) as the .mkv file is created. In fact, just finished watching "Stand by Me" on Kodi via my own media server, and it looked / sounded terrific.
Again, I know this is kind of a pain, and I know that soon enough, Mike will have MKV to the point that it can handle AACS 2.1 discs on its own. When that happens, for me, it's goodbye DeUHD. But for now, this works. Hope it helps. Have a great Labor Day!