Beam gen 2 only gets PCM 2.0

Any home theatre device is dependent on the signal being sent to it. Is your pc producing a 5.1 signal? How are you connected?

Also, have you looked at this: 

• Using Sonos as PC Speakers Tutorial

It’s connected via SPDIF, with an adapter connected to the HDMI cable that connects to the Beam. It was the only way I found to make the soundbar to “stream” my PC’s sounds.
My GPU is a RTX 4080, so it is capable of producing a 5.1 signal. But neither in the app nor in the PC I can change successfully the signal for 5.1, it just remains on 2.0/2.1

That was the tutorial I followed, yes. It fixed the connection with computer, but created another “problem”, which is the signal

And as asked already: what is your source? If what you’re watching is only 2.0 that’s all the Beam can reproduce. 

It didn’t create a problem; it may have identified one. 😜

Sorry, I understood something else from the question.

I tried multiple movies and series with 5.1 sound. I watch them via Kodi

You can’t get PCM 5.0 over optical.

You can get DD 5.1 if you have the codec.

I tried searching for that codec but couldn’t find it anywhere. Do you know where I can get it?

The most straightforward way to get 5.1 channel sound out of a Windows PC via SPDIF is to use an add-on sound card. I use a Creative Sound Blaster Z SE, which supports both Dolby Digital Live and DTS Connect. (DD Live and DTS Connect both do “on the fly” encoding of uncompressed 5.1 audio sources like games.)

So far as I know, current motherboards only produce uncompressed (PCM) audio and that limits you to two channels via SPDIF because of bandwidth limitations.

I’m using a Beam (Gen 1) plus a pair of Play:1s and a Subwoofer Mini for my PC audio. It sounds great but I wouldn’t have done it if I didn’t have the Beam and Play:1s left over from upgrades. Well, that plus it was kind of cool to do. It’s not the most natural way to get 5.1 audio from a PC. And certainly not the cheapest if you buy new.

I neglected to mention the other problem with getting 5.1 out of a PC, which is first getting it into the PC. I use my PC audio for gaming rather than media watching and my setup works fine for games -- at least for the ones that actually produce 5.1 audio. I can also get 5.1 from my Plex server and from the VLC media player on the rare occasion I want to watch some pre-recorded media.

Getting 5.1 from streaming sources via web browsers is another matter, since that support is generally lacking. The Netflix help center, for example, states that “5.1 surround sound is not supported while watching downloaded titles or while using a web browser.”

To get the Beam Gen 2 to deliver PCM 5.0 or Dolby, you'll likely need to check your PC's audio settings and make sure it's set to output surround sound. Also, ensure your soundbar is connected via HDMI ARC or eARC, as those are essential for higher-quality audio formats like Dolby. If you’re still stuck, you might want to check if your PC’s sound card or drivers support these formats, or consider using a third-party app to help manage audio output