Bose Smart Ultra Soundbar keeps disconnecting

A Smart Ultra Soundbar that keeps dropping out is usually either a Wi-Fi or Bluetooth connection problem or an HDMI-CEC handshake that gets lost. Bose's grouped-speaker checklist reads the Wi-Fi Strength value in Technical Info (-30 dBm is best, -90 dBm poor), suggests the router's other band and a fixed channel, and says to bypass extenders. For HDMI drops, use the CEC options in the app, where Option 5 is meant for a link that is lost and does not come back.

Part of Bose Smart Ultra Soundbar troubleshooting guide

Differential

Likely causes of “Bose Smart Ultra Soundbar keeps disconnecting”, and how to tell them apart

1
Weak Wi-Fi signal
What separates it Streams stutter and the app reports the soundbar offline
How to confirm Read the Wi-Fi Strength number in Technical Info and move the router or soundbar closer
2
A busy wireless channel
What separates it Dropouts cluster at peak evening hours when many devices in the home share the router
How to confirm Set a fixed channel such as 1, 6 or 11 on the router
3
A CEC handshake failure
What separates it The TV loses the soundbar every time it sleeps
How to confirm Try HDMI Power and Audio Option 5 or Option 6
4
A range extender in the path
What separates it Only the soundbar stutters when the extender is in use
How to confirm Connect the soundbar to the main router or move it within range of it

Before you touch a setting

Record this first — changing settings destroys the evidence

The Wi-Fi Strength reading in dBm from Technical Info
Whether Bluetooth, HDMI or Wi-Fi is the connection that drops
What times of day the drops occur and what else is running

Try in this order

0 of 5 completed

Find the Wi-Fi Strength
Reversible
In the Bose app choose Settings then Technical Info and read Wi-Fi Strength. Numbers near -30 dBm are strong; readings near -90 dBm are poor.
Improve the router link
Reversible
Reboot the router for 30 seconds, choose a fixed channel, and try the other band on a dual-band router.
Remove extenders
Reversible
If an extender, repeater, powerline adapter or access point sits between the soundbar and the router, connect to the main router and retest.
Adjust CEC
Reversible
Open Settings, Power, HDMI Power and Audio and choose Option 5 for a lost HDMI link or Option 6 if the TV turns back on.
Power reset
Reversible
Remove power from the soundbar and accessories for 30 seconds, then reconnect and wait about 30 seconds.

Model-specific

What is true of this model and not of its siblings

Mic and error lights: The microphone LED is off when the voice assistant is enabled and red when it is disabled. Amber flashing four times is a source error; red flashing four times means the voice assistant or internet is unavailable.
Accessories: The optional Bass Module 700 and surround speakers need their own power cords; disconnect them too when doing the 30-second reset, then reconnect after the soundbar boots.
Error and notification lights: A yellow pulsing bar is a voice assistant notification, amber flashing four times is a source error explained in the Bose app, red flashing four times means the voice assistant or internet is unavailable, and a solid red bar is a system error with its own troubleshooting article. Green pulsing means ready for setup or recovery mode.
HDMI and optical: Connect the supplied HDMI eARC cable to the soundbar and the TV's eARC or ARC port, or use the optical cable if the TV lacks one. In the TV menu look for ARC or CEC options and set the sound output format to PCM. If sound is still odd, try a different high-speed HDMI cable.

Stop boundary

When this stops being a self-service repair

!If it drops even wired to the router after a factory restore, request service
!If the drop happens only when the TV sleeps, contact the TV maker about CEC after trying Bose's options

Evidence ledger