Apache doesn't listen on all ports configured with virtual host and reverse proxy

Tibor Nagy asked:

I have a host (Ubuntu 16.04) and a virtual machine on it. I want to use apache to forward different ports to the VM with the reverse proxy modul. The problem is, that apache doesn’t listen on all configured ports.

I have the following settings in /etc/apache2/sites-enabled/moni1.softxs.ch:

<VirtualHost *:80>
    ServerName          moni1.softxs.ch
    Redirect            301 / https://moni1.softxs.ch/
</VirtualHost>

<VirtualHost *:443>
    ServerName          moni1.softxs.ch
    ProxyPreserveHost   On
    ProxyRequests       Off
    ProxyPass           / http://172.16.3.101:80/ retry=0
    ProxyPassReverse    / http://172.16.3.101/
    SSLCertificateFile /etc/letsencrypt/live/moni1.softxs.ch/cert.pem
    SSLCertificateKeyFile /etc/letsencrypt/live/moni1.softxs.ch/privkey.pem
    Include /etc/letsencrypt/options-ssl-apache.conf
    SSLCertificateChainFile /etc/letsencrypt/live/moni1.softxs.ch/chain.pem
</VirtualHost>

<VirtualHost *:3000>
    ServerName          moni1.softxs.ch
    ProxyPreserveHost   On
    ProxyRequests       Off
    ProxyPass           / http://172.16.3.101:3000/ retry=0
    ProxyPassReverse    / http://172.16.3.101/
</VirtualHost>

<VirtualHost *:3010>
    ServerName          moni1.softxs.ch
    ProxyPreserveHost   On
    ProxyRequests       Off
    ProxyPass           / http://172.16.3.101:3010/ retry=0
    ProxyPassReverse    / http://172.16.3.101/
</VirtualHost>

I can see with netstat, that apache doesn’t listen on port 3010. No idea, why.

$ netstat -nlptu | grep apache2
tcp6       0      0 :::80                   :::*                    LISTEN      32252/apache2   
tcp6       0      0 :::3000                 :::*                    LISTEN      32252/apache2   
tcp6       0      0 :::443                  :::*                    LISTEN      32252/apache2 

The port is free, I can listen on it with nc. All other reverse proxy setting are working as expected.