Ensure the file name matches what the device expects (often case-sensitive).
Disable your firewall for those five minutes—nothing kills a firmware flash faster than a "helpful" security block. i tftp upgrade firmware version 1255 download new
You might wonder: Why not use HTTP, FTP, or a USB stick? TFTP (Trivial File Transfer Protocol) has unique advantages in the upgrade ecosystem: Ensure the file name matches what the device