[users] apache connection time out and reconnects after the remote remote ip has changed (Apache Users)

I installed Apache/2.2.22 Ubuntu 12.04. Apache is set as reverse proxy server.

So when accessed from a remote system, the page and contents are

displayed. But after some time the server seems to refuse any further

requests. The remote browser console gives "net::ERR_CONNECTION_TIMED_OUT"

error. But when the ip of the remote machine changes (using a dongle which changes ip after
every connect/disconnect), the page/contents displays again.

But the above said issues occur again.

Their is tomcat7 running along with apache. Tomcat is serving the jsf page through port 8080. All the other requests are handled by apache, proxy it to

a virtual machine.

In apache2.conf file i mainly changed these directives

    Timeout 1800
    KeepAlive On
    MaxKeepAliveRequests 0
    KeepAliveTimeout 5
    Include proxy.conf

In proxy.conf

    <VirtualHost *:3000>
        ErrorLog ${APACHE_LOG_DIR}/cartodb_error.log
        LogLevel debug
        <Proxy balancer://mycluster>
            BalancerMember http://cartodb.user:3002 connectiontimeout=1 retry=10 keepalive=on status=I
        </Proxy>
        ProxyPass / balancer://mycluster/
        ProxyPassReverse / balancer://mycluster/ maxattempts=10000000
    </VirtualHost>

    <VirtualHost *:8182>
    ErrorLog ${APACHE_LOG_DIR}/windshaft_error.log
    LogLevel debug
    <Proxy balancer://mycluster>
        BalancerMember http://cartodb.user:8182 connectiontimeout=1 retry=10 keepalive=on status=I
    </Proxy>
    ProxyPass / balancer://mycluster/
    ProxyPassReverse / balancer://mycluster/ maxattempts=10000000
</VirtualHost>

also similar VirtualHost directives with port 8082, 8889 with similar settings.

The "cartodb.user" has been aded in the /etc/hosts file to redirect it to virtual box.

Also the firewall has been disabled for the virtualbox. vVirtual box is also having

Ubuntu 12.04.

In ports.conf

    NameVirtualHost *:80
    NameVirtualHost *:8889
    NameVirtualHost *:8082
    NameVirtualHost *:8182
    NameVirtualHost *:3000
    Listen 80
    Listen 8889
    Listen 8082
    Listen 8182
    Listen 3000

The enabled modules are

    actions.conf,actions.load,alias.conf,alias.load,authz_host.load,
    cache.load,cgid.conf,cgid.load,proxy_ajp.load,proxy_balancer.conf,
    proxy_balancer.load,proxy.conf,proxy_connect.load,proxy_ftp.conf,proxy_ftp.load,
    proxy_html.conf,proxy_html.load,proxy_http.load,proxy.load,
    proxy_scgi.load,rewrite.load

Checked the apache log files didn't give any error when loglevel is put in debug.

Please point what i have to do to create a continuous access.