What this symptom means
Bluetooth pairing, connection and the application profile are separate states. A device may show as paired without providing the audio/input/service path you expect.
Fault tree
USB / peripheral connection fault tree
Use the observation that best matches what you can reproduce. Do not treat every cause as equally likely.
Evidence: Charging works but video/data does not, or low-speed data works but high-bandwidth mode fails.
Next: Identify the cable's certified power/data capability and test a known-good full-featured cable.
Evidence: Direct connection works but the same device fails through a hub/dock.
Next: Add the dock back only after a direct baseline succeeds; check power and bandwidth sharing.
Evidence: OS sees the device but WebUSB/WebHID/Serial cannot open it.
Next: Confirm the device is actually supported by that browser API and not claimed by a protected OS driver.
Evidence: Device resets, disconnects under load or works with externally powered hub.
Next: Check host/hub power and device requirements.
Interpret the result
Evidence matrix
A test result is useful only if it changes the next troubleshooting branch.
Fast baseline
Rule out the simple causes first
- 1
Check battery level and distance/interference first.
- 2
Compare the same device with another computer/phone if possible.
- 3
On Windows, inspect Bluetooth power management and update the official Bluetooth adapter/device driver if needed.
Full sequence
Work from reversible checks to invasive ones
Do not repeatedly remove/re-pair before confirming which function fails and whether the same device works over another connection.
- 1
If multiple Bluetooth devices disconnect on the same computer, the adapter/driver/power-management path becomes more likely.
- 2
If only one accessory disconnects across several hosts, focus on that accessory's firmware/hardware.
- 3
For audio devices, distinguish a Bluetooth connection drop from an audio routing/profile switch.
Platform branches
Where the setting lives
USB-C
- Treat power, data and video as separate capabilities
- Check 60W/240W and data-rate markings on certified USB-C cables where present
- Use direct host connection for the baseline
Browser APIs
- Chromium-based support is broader for WebHID/WebUSB/Web Serial
- Permission requires a user gesture and device selection
- Some device classes are intentionally unavailable to websites
Docks
- Check upstream port capability
- Check dock power-delivery rating
- Check display topology and shared bandwidth
If the matching DeviceOK test succeeds, prioritize the affected app, browser policy, operating-system setting, or configuration before assuming complete hardware failure.
A missing browser device must be compared with OS detection and API support before calling hardware failed. Compare the simplest direct connection and official diagnostic path before replacement.
Escalation threshold
When software troubleshooting has stopped being high value
- Device not recognized on multiple hosts
- Connector is physically loose/damaged
- Cable/adapter gets abnormally hot
- Electrical smell, arcing or visible damage
- Stop using any cable, charger or port that becomes abnormally hot, sparks, smells burnt or shows melted insulation.