UBNT Discovery Tool v2.5.1 remains useful for reviving legacy airMAX or EdgeRouter devices on a flat network. On Windows 10, it works reliably only with Java 8 and administrator privileges. For modern Ubiquiti hardware, use the newer Go-based Discovery Tool or the UniFi Controller instead.

If the tool still refuses to open, you can force it to launch via the Command Prompt to see the specific error logs.

java -jar ubnt-discovery-v2.5.1.jar

This command bypasses the Windows GUI and will output a specific error code if Java cannot find the main class or if network permissions are blocked.

Running an older Java version (8u411) on Windows 10 introduces potential vulnerabilities. Mitigate risks:

Right-click UBNTDiscoveryTool_v2.5.1.exe → Properties → Compatibility tab:

Before diving into installation, it is critical to understand why you might choose v2.5.1 over newer tools.

Solution: Override Windows 10 DPI scaling.

| Feature | UBNT Tool v2.5.1 | UniFi Discovery Tool (v3.x) | | :--- | :--- | :--- | | Java requirement | Java 8 (32-bit) | Java 11+ (64-bit) | | AirMax M-series support | Full | None (dropped) | | Legacy AirGrid support | Yes | No | | Windows 10 DPI scaling | Broken (needs fix) | Perfect | | Launch speed | < 2 seconds | 15+ seconds | | Layer2 only mode | Yes | No (requires DHCP) |

Conclusion: If you maintain legacy UBNT gear, v2.5.1 is irreplaceable. For UniFi AC/HD devices, use the newer tool.