Ubiquiti sometimes keeps old builds on their CDN. Try this URL pattern (replace 4.1 as needed): https://dl.ui.com/unifi/discovery/2.4.1/
Программный поиск оборудования Ubiquiti - Ubnt.su Ubnt Discovery-v2 4.1 Free -FREE- Download
: Specifically useful for older AirMax and early UniFi devices that may not be easily found by modern controllers. Ubiquiti sometimes keeps old builds on their CDN
