Model :

Hardware Version :

Firmware Version :

ISP :

Hi
I purchased Deco M5 a while back. Initially, I used it with a 3G modem, because our ISP had not connected the landline yet (new house). The 3G modem had DHCP on its LAN ports.

Eventually, ISP established the connection in our house, and installed new modem. I specifically asked for simple modem, without any router functions, as I had had best experience with that in my old house (using an Airport Extreme). We have static IP, lets say 123.456.78.910, and previously, I just had my Airport configured to static IP, and everything worked.

Problem I have, is when connecting Deco directly to the ADSL modem, I get no internet. I try to configure as static IP, but can't quite figure out if my public IP should be configured in the IP field, or if it is gateway. I have a suspecion it is due to some mistake here.

I can get the Deco M5 system working, by connecting my old Airport Extreme to the modem with the static IP, and then set Deco as DHCP, and connect the Deco on the Airports LAN out. Light goes green, and everything is good.
I would however really like to avoid having an additional router in the mix.

Any ideas?

To sum up:
My static public IP is (example) 123.456.78.910
My ISP has delivered a simple ADSL modem with no router function.
How should I configure IP4 page of deco?