[ubuntu] How to find IP of downstream AP?

My internet comes in through a D-Link DIR-655 AP/router which has four ports. Not enough, so downstream from the 655 is a Trendnet TEG-SBOg gigabit switch. One of the 8 switch ports is connected by ethernet to the other end of the house, where I have just plugged in a D-Link DL-624 wifi AP/router.

It is receiving communication from the DIR-655 router and I can access the internet over wifi there (it is a strong wifi signal and should be up to 13 Mbps over the internet, but it is very slow. However the slowness seems to have started before I hooked up the AP there, in fact just after the last android upgrade, so maybe nothing to do with the signal.)

My android phone tells me that the IP# of the 624 AP is 192.168.0.103, but I am unable to access that address in my firefox browser on my Ubuntu linux desktop. So I used the phone to log onto the wifi of the 655 near my desktop to see what it's IP# is, and it is also showing 192.168.0.103.

So I am not understanding something fundamental here. They cannot both be .103, and if either were, I should be able to reach the admin panel at .103 and log in.

BTW, my internet comes to my house over fiber optic and there is a gateway (is this the right term?) outside my house where the optical is converted to copper digital. Could this be the 192.168.0.103, or is it something else? (it is not the 655 which is at 192.168.0.1)

BTW, what is the correct terminal command to see the IP# of the 655? IFCONFIG shows IP# of this computer as 192.168.0.106, so I deduce that the 655 is 192.168.0.1 (which does take me to the 655 admin panel), but how can I get the computer to tell me using the terminal?

Please walk me through this. Thanks.

Edit: Moderator,

There does not appear to be much interest in the beginners forum. Would it be a good idea to move it to the networking forum?

Thanks.