Hello 2tired2care,
The steps below can help with controlling your receiver with your Siri or Apple TV Remote:
If volume control doesn’t work automatically, you can manually program your remote to control volume on your TV. Open Settings on your Apple TV. Then go to Remotes and Devices > Volume Control > Learn New Device, and follow the onscreen instructions.
Clear the path between your remote and the front of your TV or receiver. Volume control normally works using the IR sensor* on the front of your equipment.

Make sure that HDMI-CEC is on
If your TV or receiver supports HDMI-CEC, Apple TV uses the HDMI connection to allow it to be controlled by your TV or receiver remote.
If some features don't work:
1. Make sure that your TV or receiver offers HDMI-CEC support. For help, ask the TV manufacturer or check the manual.
2. Check that your Apple TV is connected to an HDMI port that supports HDMI-CEC. Check the TV manual to confirm which ports support HDMI-CEC.
3. Check that HDMI-CEC is turned on in the menu of your TV or receiver. Use the remote that came with your equipment. Because manufacturers often have different names for HDMI-CEC, look for a setting that ends in "Link" or "Sync." Here are some examples:
• Sony: BRAVIA Sync
You can also find those steps in this resource: Control your TV and volume with the Siri Remote
Should that still persist, you may need to reach out to the manufacturer of your sound bar to get more details on their compatibility with Apple TV: Bose Product Support
Take care.