Using Debian Bookworm, I’ve noticed that quite often the RSSI is set to 0 in Bluetooth advertisements received during a scan. I’ve seen this consistently before and after an apt upgrade and on multiple Rock Pi S modules. I did not have this problem with Debian Buster. All I have to do is launch “bluetoothctl” and enable scanning to see this. I have quite a variety of bluetooth-enabled devices nearby so it doesn’t take long to see advertisements with RSSI set to nil.
[CHG] Device 46:9C:5B:86:BA:76 RSSI: -80
[CHG] Device 76:02:36:3A:C4:AA RSSI is nil
[CHG] Device FF:3B:29:82:29:88 RSSI: -66
[CHG] Device 5F:B1:60:29:AF:0C RSSI: -66
[CHG] Device A0:E7:AE:62:AA:F9 LegacyPairing: yes
[CHG] Device A0:E7:AE:60:A9:2C LegacyPairing: yes
[CHG] Device A0:E7:AE:60:A9:2C RSSI: -64
[NEW] Device E2:44:EF:40:F1:A6 Charge 2
[CHG] Device FF:3B:29:82:29:88 RSSI is nil
[CHG] Device 5F:B1:60:29:AF:0C RSSI is nil
[CHG] Device A0:E7:AE:62:AA:F9 LegacyPairing: no
[CHG] Device FF:F8:FD:D4:FC:34 RSSI is nil
[CHG] Device A0:E7:AE:60:A9:2C LegacyPairing: no
[CHG] Device A0:E7:AE:60:A9:2C RSSI: -72
A problem in the rtl8723ds driver perhaps?