Sony alpha 7 R IV Instruction Manual page 441

Help Guide
Interchangeable Lens Digital Camera
ILCE-7RM4
α7RIV
USB LUN Setting
Enhances compatibility by limiting of USB connection functions.
MENU → (Setup) → [USB LUN Setting] → desired setting.
1
Menu item details
Multi:
Normally, use [Multi].
Single:
Set [USB LUN Setting] to [Single] only if you cannot make a connection.
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