Can't configure correctly codecs to pass 5.1 from PC -> HDTV -> HomeTeather

Hi everyone! (first of all, sorry for my english, not my first lang!)
I  have this problem for almost a year now, just living with it, but it get me really annoyed now..
The thing is i can't pass a correct 5.1 audio from my pc (nvidia 1080ti hdmi out) to the hdtv that is conected with a HDMI Arc to my sony home teather:

Case 1:
[ PC ----nvidia hdmi---> Sony HDTV <----Arc Hdmi--> Sony Home teather ]
         In this case, i almost got perfect 5.1 via passtrough, i downloaded a test mp4 audio file to check if all the 6 speakers worked like they should (rear, front.. right.. etc) touching here and there the codecs and filters of my favorite media reproductor(Potplayer) i managed to get it to work fine yay!.
Windows showed me a 5.1 option enabled on the audio tray, but both rear and subwoofer did not worked like they should (rear sound test was played on the front speakers, also subwoofer didnot sound at all on the windows test).. it was fine since only windows sounds where wrong.. but no, all games where working wrongly too, i checked it with middle-earth - shadow of war integrated sound testing, and the result was almost the same as windows tests.. rear sounds played on the front speakers.
I installed k-lite code pack.. touched everything but  nothing worked, maybe because of my short knowledge.

Case 2:

[ PC ---Nvidia Hdmi with just video--> HDTV <---Arc Hdmi--> Home Teather ]
   ^-----------------Optic Link----------------> ^

I disabled the audio from the nvidia hdmi.. no sound at all, at least from the PC. tested the three options from the HDTV about passing compressed audio, compressed with multiple channels, and PCM. Nothing.

Case 3:

[ Home Teather <-----Optic Link----- PC ----Nvidia video/audio---> HDTV ]

Work like case 1, but not a option since this disable the hdmi control from the hdtv over the home teather and i need to change cables every now and then to watch netflix and what not.


*Home teather only have one Out HDMI (arc)

Thanks in advance!!.. this has been my nemesis for a year now!

MP4 files usually contain AAC audio, for which direct passthrough (=bitstreaming) is not possible. The audio is decoded on the computer and send as PCM (= uncompressed audio) to your TV/receiver. Bitstreaming is possible for formats like AC3 and DTS.

If you only hear sounds from the front speakers, then something in the playback chain is mixing the audio to Stereo. Most audio decoders have a Mixer option in it settings. So check those settings. Potplayer also has an audio processing filter (I think). Either disable that, or configure it so it outputs 5.1.

Now for cases 2 and 3. With an optic link (SPDIF) it is not possible to passthrough 5.1 PCM. That only supports Stereo PCM. It also supports bitstreaming of 5.1 AC3 and DTS. If you want 5.1 for other formats, you need to use AC3Filter as decoder, as that has an option to convert audio to AC3.