Site survey adapters are often specialized devices with enhanced sensitivity and performance characteristics compared to standard client Wi-Fi adapters.These specialized adapters can detect weaker signals and provide more detailed RF information, leading to higher RSSI readings during surveys.Consequently, standard client devices may experience lower RSSI values in the same environment.

The CWDP-305 Official Study and Reference Guide notes:MetaGeek Community

"Survey adapters are typically more sensitive than standard client devices, which can result in discrepancies between survey data and actual client experiences."