Even the best tools hit snags. Here is a troubleshooting hierarchy.
Ubnt Discovery-v2 is a software tool developed by Ubiquiti Networks, Inc. (Ubnt) to help users discover and configure their Ubiquiti devices, such as routers, switches, and access points. Ubnt Discovery-v2 4.1 Free -FREE- Download
For Linux/macOS, use ubnt-discovery-cli : Even the best tools hit snags
Instantly see the IP address, MAC address, and firmware version of any Ubiquiti device on your network. Reboot/Web UI Access: such as routers