If you’re reading this you’re that means you don’t need further introduction to the problem, let go straight to solution then ;).

tftp 192.168.11.1
tftp> verbose
tftp> binary
tftp> trace
tftp> rexmt 1
tftp> timeout 60
tftp> put wzrhpg300nh-176 # this is the filename of downloaded firmware

More references: 1, 2. Good luck!