Ubiquiti does not publish a firmware named “1-255”. That string appears in some community scripts or outdated wiki examples for mass upgrades via CLI or AirControl.
To successfully navigate the "Version 1-255" lifecycle, a rigorous protocol must be followed. First, backups are mandatory. Before initiating any download or upgrade, the device configuration must be exported and saved externally. This ensures that in the event of a configuration corruption—a common side effect of major version jumps—the network can be restored rapidly. --- Upgrade Firmware Version 1-255 Ubnt Download
ssh ubnt@192.168.1.20 # password: ubnt cd /tmp/ wget http://your-local-server/XM.v1.255.bin ubnt-upgrade /tmp/XM.v1.255.bin Ubiquiti does not publish a firmware named “1-255”