I checked the log files, the only line for my pc (192.168.1.100): GET / HTTP/1.1
After that, I installed lynx (terminal browser) to the machine, and it works on fine localhost:10000... I tried it without windows firewall, and on another machine: still "Connecting...", or 'Waiting for..." forever, after accepting the certificate. It may be my router, but putty (ssh) is working well, and the following message appears too if i only put http, not https:
This web server is running in SSL mode. Try the URL
https://192.168.1.103:10000/ instead.
I set SSL=0 in /etc/webmin/miniserv.conf, and restarted webmin. There's no message now, it's just connecting forever without https too...