When you say you want to "bridge" the rooms together, I take it that you mean you want to "connect them", not that you want to really bridge them. I say that because later, you say that the linksys will act as a router.
Well, irregardless, I you are looking at 2-4 networks here.
Network A - the Internet, to the ISP, Linksys routing between this network and the LAN
Network B - the Internal LAN on the inside of the linksys
Network C - the WAN between the linksys and the dlink
network D - the lan (wireless) on the inside of the dlink
Now, option 1 is that the linksys is really a real router and can route on all ports. Thus, it is routing between the WAN connection to room 2 and the other ports - the are all different subnets. With this, you end up with 4 networks.
Option 2 - the linksys is just a regular wireless AP & home/small business router that has 1 WAN port and a 4+ port switch. you are connecting that internal switch port to a long ethernet cable (that you called a WAN) and running it to the dlink. Really, everything on the internal LAN of the linksys (including the dlink WAN port and the DLINK LAN ports) are all on the same IP subnet.
In option 2, you only have 2 networks-
Network A - the Internet
Network B - the internal LAN from linksys, the connection between linksys & dlink, and the wireless & internal LAN of the dlink.
In that case, the dlink is really just a wireless AP (a bridge). You would want to turn off routing on the dlink and connect the ethernet cable from the linksys just to the internal LAN ports - not using the "Internet/WAN" port on the dlink.
I think you are option 2.
I hope that helps.
Let me know.
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