LinkSys E2500 ports wont open

Question

Hi, my LinkSys E2500 wont open my ports, I have tried DMZ mode but it still does not open any of the ports.
How do I fix this?

Answer 1

the lan ip address for the modem/router is public
heres the status to my router:
Connection Type: 
Automatic Configuration - DHCP
Internet IP Address: 
10.0.0.9
Subnet Mask: 
255.255.255.0
Default Gateway: 
10.0.0.1
DNS1: 
75.75.76.76
DNS2: 
75.75.75.75
to access the modem/router UI, i use ip address: 10.0.0.1
to access my router UI, I use ip address: 192.168.1.1
i accessed the modem/router UI and set DMZ on ip address 10.0.0.9,  going off of the link providided to me by jlbjlb, but the ports are still closed.
The Make and model of the modem/router is XFINITY Wireless Gateway TG862G/CT
(NOTE): everytime I access the modem/router UI, I can only access the advanced tab (port forwarding, triggering,DMZ), if i try to access anything else the UI becomes unresponsive.
it looks like I have private ip from my modem/router, right? how do i fix it if so?