Cannot PUT or GET from/to TFTP server on 'Included' machine

The ‘Included’ machine doesn’t seem to be working correctly. The suggested exploitation is the upload of a reverse shell to the TFTP server. From my local system (yes I’m connected to VPN), I can connect and even send a status request to the server, to which it responds in a predictable manner. However, whenever trying to PUT or GET any file, the transfer times out. I’ve tried increasing the timeout to no avail. Really frustrating. I know this issue has been raised before. Any ideas? Is this box just not configured properly?

tftp> status
Connected to
Mode: octet Verbose: on Tracing: off Literal: off
Rexmt-interval: 5 seconds, Max-timeout: 25 seconds
tftp> put some.txt
putting some.txt to [octet]
Transfer timed out.

Just as a quick update for those interested; Wireshark showed no traffic passing over the VPN tunnel when PUTing the file. I suspect the TFTP client is trying to bind to the incorrect local interface. Using pwnbox it all works fine.