A common gotcha: The sniffer firmware is stripped down . It does not support connection filtering by BD_ADDR in hardware. You have to filter in Wireshark post-capture. This means if you are in a dense office with 50 BLE devices, your sniffer will oscillate wildly trying to follow random connections unless you use the --target flag.

Here is how it works on a technical level:

The nRF Sniffer is a debug tool that allows developers to listen to the Bluetooth LE radio traffic exchanged between devices in real-time. It creates a "wiretap" for the air, capturing every packet transmitted within range.