Hi,
I've bought a 5.1 home theater sound system (Sony HT-RT3), that supports only Dolby Digital 5.1 but not Dolby Atmos.
My Philips smart tv Netflix app, supports only Dolby Atmos for 5.1 surround sound.
Netflix from PC (connected to the TV) has 5.1 and works fine.
I am looking for an alternative solution. Maybe some Android box, that is supported by Netflix and it supports Dolby Digital 5.1?
If your receiver doesn't support atmos then your Netflix app should recognise it as such and offer only 5.1 instead of atmos, not sure why it doesn't do that.
Can you connect it via optical from the tv? it should transcode DD+ 5.1 to DD 5.1
Netflix uses Dolby Digital Plus (DD+) for it's 5.1 channel sound tracks. DD+ is basically a super-set of Dolby Digital (Which is close enough that it can also be called AC3). You will need something in the chain that either converts DD+ to DD, or simply ignores the extra stuff and treats DD+ as if it was DD. When you play from your PC, one of the drivers and/or codecs on your system is doing that.
I could be wrong, but I believe the only way you will get 5.1 sound from a Netflix app is via your PC, or by upgrading to a surround system that support DD+.
It's worth noting that Disney+ uses EAC3 which is very similar to DD+ (If your gear supports one, it usually supports the other) so you are going to have almost exactly the same problem there.
It seems weird to me that your Netflix app only supports Atmos. I also have a Philips smart tv and initially had problems setting up my surround. You have to manually set the audio options on your tv to surround.
Settings - All settings - Sound - Advanced - “... digital output” - Dolby Digital Plus