UPnP malfunctioning on WRT1200AC and ATT Z700A

[minifig3d]

Hello,
I have my internet through AT&T, but their modem/router box (the "ATT Z700A") only allows for 10 devices to connect to the wifi, and I have more than that. So I got a Linksys WRT1200AC and have the ATT plugged into the WAN port.
OK, that's my setup, now for my issue. I have 4 laptops that connect to the network to play a game called Warframe, which worked fine on my old internet which used a cradlepoint modem and UPnP was perfect. With this setup though, it does not work at all. The ATT does say it has UPnP enabled, http://i.imgur.com/aoYdt0a.png as does the Linksys http://i.imgur.com/z83YenQ.png , but when any of the computers launches Warframe, it still gives us a "Strict NAT detected. UPnP malfunctioning." error. I would like to avoid port forwarding if possible, as there are a lot of other games we play and needing to set up ports for each would be tiresome.
Any tips or thoughts on my best way to set this up?

 

[nigelivey]

UPnp will not work when you pass the connection through 2 ROUTERS and portforwarding this set up is also a pain, you need to either replace the ISP gateway device completely with your Linksys, or bridge the connection from your ISP device to your Linksys.

 

[minifig3d]

UPnp will not work when you pass the connection through 2 ROUTERS and portforwarding this set up is also a pain, you need to either replace the ISP gateway device completely with your Linksys, or bridge the connection from your ISP device to your Linksys.

May I ask what bridging the connection would consist of? If this will fix the issue, I will try it, for sure.

 

[nigelivey]

It should be a setting on your ISP device that basically turns it into a modem only, and passes the WAN connection through to your Linksys, in essence the ISP device becomes transparent and performs no other function but that of a modem. (Performs no routing). This may not be possible, do you use the voice service (IP) on the device? Another option would be to put the IP address that the Linksys picks up in the DMZ of the ATT device, this is available in the settings. Look at the config page of the Linksys, make a note of it's WAN IP, go into the ATT device look for DMZ and input the IP address of the Linksys. See if that works.

 

[minifig3d]

I tried putting the Linksys as the DMZ of the ATT device, but sadly no-go. After some research, it seems nobody can get this ATT device to let them port forward at all. Or else it is blocking all ports other than port 80 for internet browsing.