Use other transport instead of TFTP
TFTP is unreliable on some networks.
It is using UDP and not a TCP socket.
1) Change to a plain socket interface
2) Use simple HTTP server and protocol (more code/overhead, but has the option of hosting a web interface to download and view jobs)
For option 1 there needs to be some protocol to send metadata (like the job name to show on the display).
It could be simply the first line of the file, or lines that start with ";;" or something similar.