I am not getting any sound when plugged into a Receiver. I’ve tried everything.

Welcome to the Apple Community.

Have you tried adjusting the “Audio Output" and the “Surround Sound" settings in Settings ➔ Video and Audio? (Apple TV 4/4k) It may be worth trying several combinations of these settings, although typically it is the “Surround Sound" setting that causes most problems for users.

If you are using a sound system/receiver, make sure that you have correctly mapped the input port on your sound system to the output, if you are unsure about how to do this, refer to the manual that came with your sound system.

Have you tried playing various content sources (i.e. podcasts, music, iTunes Store video, other videos etc), do you have the same problem with all types of content?

Firstly, sorry, I meant “Audio Mode” rather than Audio output for the Apple TV 4.

Audio mappings are settings on the receiver that allow you to map (say) the video from “HDMI input 3” and “optical input 1” to “HDMI output 1”, in other words it lets you mix and match inputs.

Other than the settings on the Apple TV that I have mentioned, I'm not aware of anything else that can affect the audio output, as such I'm inclined to think it's the receiver or it's settings. however, if you aren't convinced, why not take it to an Apple store and have them check it.

I have an Apple TV connected to a receiver that dates from before HDMI 2.0 (indeed, I'm reasonably confident it predates 1.4) and it works just fine, so your advice seems quite questionable.

Incidentally, there is no such thing as HDMI 2.0 cables.

I do not have a sound system as my setup is AppleTV → Receiver → TV.

Does that mean you intend to use the internal speakers of the TV for your audio output? That would be different from what many users want: better speakers than the TV has, connected to a receiver. If you intend to bypass the receiver for audio processing, then the app control may not work. You may need HDMI-CEC all through the chain (supported and turned on) on all devices for app support, although volume control may stop at the receiver anyway.

On my setup, the choice between TV Sound and AV Sound is made on the tv with an HDMI Control menu. When set to TV Sound, neither the receiver nor the app controls the volume.

Some receivers have an HDMI Audio Out setting, that has to be turned ON to allow other comports to receive Audio.

If the TV can’t play (downmix) surround sound, then it may ignore the multichannel audio stream (no sound at all). Try setting Video & Audio > {Audio:} Surround Sound to Stereo on the Apple TV. Does that make a difference?

In my case the volume buttons (in regard to my Apple TV remote app) on the phone do not adjust the volume, but they won't in all cases and I hadn't expected mine to.

In regard to HDMI, as per previously suggested, I don't believe this to be related to HDMI specifications.

As the audio settings on the Apple TV don't make any difference, I can only assume it's most likely the audio mapping on the receiver.

For clarification are you using external speakers connected to the receiver, I had assumed you were.

There is an Apple article that says that volume control on the phone will work when hooked up to specific receivers

Yes, that's correct, many set ups require IR which of course the phone doesn't do.

I have just been trying to use the internal speakers on the TV up until this point

Can I ask why you need to go through a receiver, then?

I have an Onkyo TX SR605, having checked it is HDMI 1.3a compliant.