As per my post above, it seems likely that the Nginx server does not have the appropriate permissions to access the socket (assuming that the socket exists).
I suggest trying something like this:
ls -la /var/lib/lxc/nas/rootfs/usr/share/mayan-edms/uwsgi.sock
As a general rule, the root account should have access to everything, but obviously Nginx doesn't run as root. The default webserver account for Debian is 'www-data'. One way to ensure that Nginx has permission would be to give everyone full access to it. Note that is almost always extremely poor practice, with testing being the only legitimate exclusion to that rule IMO.
As for the stunnel entries to the daemon log, that is expected behaviour if you're using webmin (perhaps have a browser session open?).
A permissions issue seems likely
As per my post above, it seems likely that the Nginx server does not have the appropriate permissions to access the socket (assuming that the socket exists).
I suggest trying something like this:
As a general rule, the root account should have access to everything, but obviously Nginx doesn't run as root. The default webserver account for Debian is 'www-data'. One way to ensure that Nginx has permission would be to give everyone full access to it. Note that is almost always extremely poor practice, with testing being the only legitimate exclusion to that rule IMO.
As for the stunnel entries to the daemon log, that is expected behaviour if you're using webmin (perhaps have a browser session open?).