Do you have the Netgear and Linksys connected LAN to LAN and not LAN to WAN? Is DHCP turned off on the Linksys? Your devices need to pull IPs from the Netgear and not the Linksys.
You will need to open ports for the IPs of the computers and the XBox on the Netgear, and reserve those IPs so they don't change for those devices.
You may want to consider purchasing a dedicated network switch, some available for around US$20.
Okay so this is an issue which i gave up on about a year ago. I used to run a multitude of servers from home computers (such as minecraft servers) and the issue i am running into is now i can not.
Almost a year ago i moved houses obtained a new internet plan and a new Modem (i am not sure of the names of the newer versions which have inbuilt routers and wireless capabilities, but this is one of them). When i connect directly to this Modem i can port forward and my ports are found to be open when using a port checkers. The the next part is where i ran into some issues, i run two computers and an Xbox and wireless is pretty much out of the question seeing as i have a foot thick concrete wall which blocks any to all signals form traveling through. To work around this i run one hugely long cable to a older router (Cisco Linskey E-2500) and connect my xbox and computers with individual cables. The issue is now that i have both a modem(routerthingo) and a secondary router which acts as a switch, i can no longer port forward in a way that anything can connect to my PC. When testing with external Ip address its comes up as closed. i attempted to open the port on the primary router for both my computer ip and secondary router ip, i then went on to open the port on my secondry router think that it was just like have two doors which needed to be opened. none of this work and i really would like a hand in fixing this if anyone has any ideas.
Specs of things:
Primary Modem (router wirlesthingo): netgear CG3100
Secondary router/switch: Cisco Linksys E-2500