I added webmin rule in Google Cloud Dashboard> VPC Network > firewall rules already. Actually it worked normally many days before. However, today I cannot access webmin.
sudo netstat -anlp | grep :10000
tcp 0 0 0.0.0.0:10000 0.0.0.0:* LISTEN 1288/perl
tcp6 0 0 :::10000 :::* LISTEN 1288/perl
udp 0 0 0.0.0.0:10000 0.0.0.0:* 1288/perl