Having just spent the day working on a HS103v5, I've isolated it down to an issue between the node server and the underlying python-kasa libraries
kasa --host 192.168.xx.yy sysinfo
works ... (as does "on" and "off")
but the debug shows
2022-01-05 17:26:23,474 shortPoll kasa.protocol DEBUG protocol:query: Unable to query the device, retrying: unpack requires a buffer of 4 bytes
which implies there is insufficient bytes allotted to something. (But thats the limit of my Python skills :D)