Ok so connecting to my ATT Modem/Router to my AC-3100 in DMZ mode I only am getting 50/300, when I switch it to the Private lan on ATT Modem I am getting 900/900? Anyone else experiencing this or have any suggestions. I have been thinking it has been me but I believe it is a setting in the Modem. I have reset the modem numerous times and have went vanilla on router as well as restored with the same result. Thanks in advanced. (I am getting a new modem shipped just in case) but don't want to have the same issue.
It is a confirmed firmware issue with the 5268 AT&T supplied RG. I am internet only with gigabit fiber and I have bypassed their RG with the steps outlined below. I don't believe this option will work if you have u-verse TV. I have only had to repeat this process once, took about five or six minutes, and that was due to a power failure. You can leave the connections this way or go back to your original configuration when your new modem arrives. I have been on this setup for about four months with no issues other than the previously mentioned power failure.
1) Define your gateway's mac address on the wan port of whatever router you want to use (asus, netgear, etc). WAN connectivity should be via dhcp.
2) I'm using a simple dumb switch (Netgear GS105) to handle ONT/RGW/Router connectivity.
2a) With everything from a fully off state, allow the ONT to register (~2 min) the fiber connection first. During this time there's nothing but fiber and power plugged into the ONT.
2b) Connect ONT's ethernet port to one port of the powered on dumb switch.
2c) Connect the wan port of the RGW to another port on the dumb switch.
2d) Connect power to the RGW
3) Wait 1-2 minutes for both lights to become solid green on the RGW.
4) You can now power down and disconnect the RGW from the dumb switch.
5) Connect your router's WAN port to the dumb switch. Turn the router on.
6) Within a minute or less it should acquire the same IP, gateway and DNS as the gateway had.
7) Enjoy
"ONT reregistration will only be necessary if power to the ONT or dumb switch is disrupted. In that case, repeat steps 2b-5.