I just successfully upgraded my second QNAP TS-212P NAS
from jessie to stretch.
I didn't remember how I did the first one last year. I went to
Martin's excellent web site and did what is described as
"Re-installing Debian" from the following page:
Just before that I setup a dhcp server entry for my NAS to be
sure of the IP it would get.
This will make a nice +1 in armel's popcon statistics in addition
to the other one.
vince@debian:~$ uname -a
Linux debian 4.9.0-6-marvell #1 Debian 4.9.82-1+deb9u3 (2018-03-02)
Thanks all for the hard work put into still supporting this