You cannot typically "download and install" in one single command line string unless it is a specific script wrapping those commands (e.g., a Bash script or a specific vendor command like opkg install ).
Once the device reboots, run show version again to confirm that it is now running version 1255. 5. Troubleshooting Common TFTP Issues i tftp upgrade firmware version 1255 download install
Look for the line that begins with System image file is... and the Cisco IOS Software line to verify the version number. You cannot typically "download and install" in one
Disconnect your computer from all other networks (including Wi-Fi). Open your operating system's network adapter settings. Assign a static IP address to your Ethernet adapter. i tftp upgrade firmware version 1255 download install