Ok, so 192.168.100.1 does work if you connect directly to the second port but not if you connect through the firewall? Have a look at this post from DSLReports. Maybe you need to establish a firewall rule:
Any improvements with wifi range? I insisted on staying on my hybrid plan instead of upgrading to the ignite plans when I renewed earlier this month. I use the CGN3 as a stand alone because when I attempted to connect it to my dlink router, my speeds on wifi would go down to 10mbps dispite the fact that it's 5ghz router. Never could figure out why and gave up on it.