Dolby 5.1 through ARC?

Ut
5

I have the TV Sony KDL-32R505C now for Christmas I got the home theater system Sony BDV-E2100. An Amazon fireTV stick hangs on one HDMI connection, and the home cinema system hangs on the other (ARC connection). My problem: I don't get 5.1 sound, I only get stereo when I e.g. Watching Netflix through the Home Theater System is 5.1 no problem. Can anyone help me how I can get Dolby 5.1 from my stick to my home theater system via ARC?
Damke!

(Sorry for misspellings, got LRS)

Av

Do you have a Toslink cable?

Ut

Yes

Ut

But generally didn't work gek

Av

Connect the stick to HDMI In on the system, then from HDMI Out to the TV, then via the optical output of the TV to the system

https://www.modernhifi.de/amazon-fire-tv-stick/

Ut

The system only has HDMI-out