Hats off, SSH key-based auth works fine.
Last thing, why does PC-initiated rsync fail
Code:
sh: rsync: not found
rsync: connection unexpectedly closed (0 bytes received so far) [Receiver]
rsync error: remote command not found (code 127) at io.c(235) [Receiver=3.1.2]
, yet the binary is in the PATH?
(solved by specifying --rsync-path=/mnt/secure/bin/rsync)
@Markismus, check what process hogs CPU with htop (launch with TERM=xterm htop if it complains), sort by CPU% or look at the cumulative TIME.
Mine has eink-reader.app as top process, for instance
sftp-server: only if a long-standing SFTP transfer has occurred, which is a bit intensive for this SoC