I'm using the Zephyr hci implementation on a bt dongle. It complains that no random address is set when scan enable is sent. My RPi doesn't care if a random address is set or not. Steve btmon says: LE Set Scan Parameters (0x08|0x000b) ncmd 1 Status: Success (0x00) < HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7 #289 [hci0] 409.412208 Type: Passive (0x00) Interval: 10.000 msec (0x0010) Window: 10.000 msec (0x0010) Own address type: Random (0x01) Filter policy: Accept all advertisement (0x00) > HCI Event: Command Complete (0x0e) plen 4 #290 [hci0] 409.413191 LE Set Scan Parameters (0x08|0x000b) ncmd 1 Status: Success (0x00) < HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2 #291 [hci0] 409.413205 Scanning: Enabled (0x01) Filter duplicates: Disabled (0x00) > HCI Event: Command Complete (0x0e) plen 4 #292 [hci0] 409.429192 LE Set Scan Enable (0x08|0x000c) ncmd 1 Status: Invalid HCI Command Parameters (0x12)