When I first got my router with Firmware v1.01, under Network Settings, I was able to set the Router Address to 192.168.1.1 with subnet mask to 255.255.0.0 (My bro-in-law and I have joined networks). I updated to Firmware v1.02 and it kept the settings, but in doing some configuration changes as part of some troubleshooting, I temporarily set the subnet mask to 255.255.255.0 and when I tried to set it back to 255.255.0.0, I kept getting the error "The network id of LAN-1 is the same with LAN-2." =(
I searched this error online and found that this was an issue with a previous D-Link router, which was fixed with a Firmware update. I found the v1.04 firmware and updated to it, but the issue remained, even with it set back to factory defaults. At that point, I disconnected the device from the network with a single cable going directly to the laptop I am operating from. I then reset the device back to factory defaults and then downgraded to Firmware 1.00. With router settings completely empty and not connected to the network, I again attempted 192.168.1.1 - 255.255.0.0 with the same error. I progressively moved through firmwares v1.01 & v1.02, each time doing the same thing. At one point, I tried 10.0.0.1 - 255.255.0.0 and it allowed it. I basically found through trial-and-error that it will not allow me to use any 192.168.x.x address with subnet 255.255.0.0. (I also emailed D-Link about this problem, who asked me to call their support and I also called, spending "an hour of futility" trying things I had already tried). A fix for this in the next firmware update would be much appreciated.
Thanks! RHH