@girish I don't understand what you mean by "internal network".
However, not being able to see any other option, I have just installed Cloudron in a VM. Only when I ran the installation script (a few minutes ago) did I realize that it would be downloading a Docker image. That suggested a way out, but ...
When I ran
sudo docker ps
I could see nothing running.
sudo netstat -tuplen
shows me
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN 111 16941 1115/mysqld
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 0 16376 1127/nginx.conf
tcp 0 0 0.0.0.0:53 0.0.0.0:* LISTEN 0 16157 973/unbound
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 0 16490 1131/sshd
tcp 0 0 127.0.0.1:3000 0.0.0.0:* LISTEN 1001 18138 1283/node
tcp 0 0 127.0.0.1:8953 0.0.0.0:* LISTEN 0 16158 973/unbound
tcp 0 0 0.0.0.0:3002 0.0.0.0:* LISTEN 1001 18149 1283/node
tcp 0 0 172.18.0.1:3003 0.0.0.0:* LISTEN 1001 18150 1283/node
tcp 0 0 0.0.0.0:443 0.0.0.0:* LISTEN 0 16378 1127/nginx.conf
tcp6 0 0 :::80 :::* LISTEN 0 16377 1127/nginx.conf
tcp6 0 0 :::22 :::* LISTEN 0 16499 1131/sshd
tcp6 0 0 :::443 :::* LISTEN 0 16379 1127/nginx.conf
udp 0 0 0.0.0.0:2514 0.0.0.0:* 1001 17132 961/node
udp 0 0 0.0.0.0:53 0.0.0.0:* 0 16156 973/unbound
udp 0 0 0.0.0.0:68 0.0.0.0:* 0 12443 747/dhclient