In my home I am running a raspberry-pi based digital video recorder. To copy the recorded files to my server, I use a cron-triggered rsync script. While that worked in other situations just fine, here I always get an "error in rsync protocol data stream (code 12) at io.c(226)". Finally looking deeper into it I think I have an explanation and a solution.
For really a long time I have used a really nice feature of the X11 windowing system - remote login. That was rather easy to do. Just enable XDMCP and connecto to the X server remotely. It was not safe over the networks, but I used it only locally. My main use case was and is using the main PC in my home office from other places.
Now for a few releases the Linux distributions started to disable the protocol, or at least make it more complicated to use, as XDMCP isn't supported in the admin tools anymore.