HomePod in stereo left side cuts in and out every 30 secs

Hi Kangvik,

Since you're having audio playback issues with your HomePod, we recommend that you try the steps in the link below.

Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support

To perform the recommended troubleshooting steps via the link above, complete the steps in the section titled "How to reduce wireless interference."

These general steps can help achieve a cleaner, stronger wireless signal:

* Bring your Wi-Fi device closer to your Wi-Fi router. Bring the Bluetooth devices that are connecting to each other closer together. 

* Avoid using your wireless devices near common sources of interference, such as power cables, microwave ovens, fluorescent lights, wireless video cameras, and cordless phones.

* Reduce the number of active devices that use the same wireless frequency band. Both Bluetooth and Wi-Fi devices use the 2.4 GHz band, but many Wi-Fi devices can use the 5 GHz band instead. If your Wi-Fi router supports both bands, it might help to connect more of your Wi-Fi devices to the 5GHz band. Some dual-band routers manage this for you automatically.

* Configure your Wi-Fi router to use a different Wi-Fi channel, or have it scan for the channel with the least interference. Most routers perform this scan automatically on startup or when reset.

If you're using USB 3 or Thunderbolt 3 devices with your computer, you can limit their potential to interfere with nearby wireless devices:

* Use a high-quality, shielded USB or Thunderbolt 3 cable with each device.

* Move your USB 3 or Thunderbolt 3 devices—including any USB hubs—farther away from your wireless devices.

* Avoid placing USB 3 or Thunderbolt 3 devices on top of your Mac.

* Turn off any USB 3 devices that aren't in use.

Avoid physical obstructions in the path of your wireless signal. For example, a metal surface between your Bluetooth mouse and computer could cause the mouse to perform poorly, and a metal-reinforced concrete floor between your Wi-Fi router and Wi-Fi device could cause poor Wi-Fi performance.

* Low interference potential: wood, glass, and many synthetic materials

* Medium interference potential: water, bricks, marble

* High interference potential: plaster, concrete, bulletproof glass

* Very high interference potential: metal

We recommend the steps above because they will show you how to resolve Wi-Fi and Bluetooth issues caused by wireless interference.

If you’re still experiencing the same issue, then try the steps here: If HomePod or HomePod mini isn't responding - Apple Support

Please let us know the outcome after giving the above steps a try.

Thanks for using the Apple Support Communities.

Cheers!