When working with software images like air-ct2500-k9-2-0-0-0-fus.aes , administrators should follow best practices:
The file air-ct2500-k9-2-0-0-0-fus.aes is the for the Cisco 2504 Wireless LAN Controller (WLC) . Unlike standard firmware (RTOS), FUS is a special package used to update critical system-level components like the bootloader, field recovery image, and FPGA/MCU. Critical Pre-Installation Notes air-ct2500-k9-2-0-0-0-fus.aes
Use a stable server (like SolarWinds or FileZilla) to move the file to the WLC. field recovery image