Hi,
I'm as you can see new to setting up network and I suspect maybe I have bought the wrong equipment for what I would like to do

. But before I go out and do new mistakes I would like to see if what I would like to do is possible and if it could be done with what I have... I have tried to search the net for solutions, but I haven't found anything useful (probably I don't know the correct search terms)...
I have a network coming in to my house via a Thomson TG784 with two ports occupied by television output and thus two ports left for data. One of these is connected to my stereo and one should be connected to my office on the second floor. The TG784 also have WiFi (let's call it WiFi1). In the office I would like to connect one stationary workstation, one NAS and from time to time a laptop, but I also need to extend the WiFi range. For this I bought a DIR-652 and it sort of works, but not as I would like, since the office network becomes a separate network (or subnet?) from the one on the first floor with the stereo and WiFi1, with a new WiFi net (WiFi2). I now can't connect the NAS to the stereo and when I use wireless devices it depends on which WiFi I am connected to if I can access the NAS or the Stereo (via AirPlay).
Is there a way to configure DIR-652 so that I get three new wired connections and an extended range of WiFi1 in my office on the same network (subnet?) as if it was connected directly to the TG784 (as if the TG784 would have had more wired ports and a stronger WiFi)? If so, please be as specific as possible on how to do it... If not, what equipment would I need to set it up the way I want it?
Best regards
Anders