I have a set of about 20 embedded Unix clients who physically move from time to time. When they move into the range of a specific wireless AP, they will push a certain set of files to a Windows file server in the LAN. Every client will send a 250Mib file. There will never be any remote access to this LAN.
It basically looks like a train (embedded Raspbian clients) on a traintrack collecting passengers (the files) and then dropping them off at a specific point (The windows server).
I only want to push files to this Windows server and get an acknowledgement that it completed or not. I don't want or need anything else. I'm not going to share files between the clients or the server, files won't be modified or anything else than just a barebones bulk upload of files. The clients will never interact in any other way with the server or files other than uploading them. The server will process these files further.
To summarize: Which protocol is most suitable for solely uploading files to a server?