Filing a fresh 2026 data point on a multi-year, still-unsolved issue. Closed prior thread: en.community.sonos.com/home-theater-228993/beam-keeps-switching-back-to-arc-from-bluetooth-how-to-stop-not-solved-6925022
Setup:
- TV: LG OLED C5 (latest webOS firmware)
- - Soundbar: Sonos Beam Gen 2, connected to TV via eARC
- - Headphones: Sony WH-1000XM5 over Bluetooth
Repro (every time):
1. Pair the WH-1000XM5 to the TV. Connection succeeds.
- Settings -> Sound → Sound Out -> set to Bluetooth Audio Device. Audio routes to headphones.
- 3. Within ~5 seconds, the TV silently reverts Sound Out back to HDMI ARC Device (the Beam) on its own. Audio is back on the Beam, headphones go silent.
- 4. Disabling SIMPLINK (HDMI-CEC) on the LG side at Settings -> General -> Devices -> HDMI Settings does NOT stick — the toggle re-enables itself within seconds while the Beam is on the HDMI bus.
The only reliable workaround is physically unplugging the Beam HDMI cable, which is unacceptable for premium gear.
The Beam aggressively re-asserts CEC presence when powered, which is what triggers the LG TV to re-enable SIMPLINK and re-route audio to ARC. Both Sonos and LG own a piece of this.
Feature request to Sonos: add a “silent on CEC bus” / "do not announce on power-on” option in the Beam Sonos app settings. OR honor a "headphone mode” / "user-overrode-output” signal from the TV and refrain from waking on CEC for a configurable cooldown.
The issue has been documented across LG OLED generations BX, CX, C2, G1, G4 and now C5 — a multi-year regression with no resolution. Tagging this for engineering attention.
