The cable that enter is connected to the NIU. From there there's a connection to a motorola modem (SBV6120E -Its not wireless so I don't think this is a router but not sure).
Between the Dlink router and the modem there is a DLINK switch (DES-1005D).
From the sound of it, that just doesn't seem right..I acronymfinder'd "NIU" and it sounds like "NIU" would be your computer, and this quote sounds like it's set up like this...:
internet comes in from the wall -> dlink router -> dlink switch -> motorola modem -> your computer
From what I'm seeing you write, that's what it seems, and if that's the case, then it looks like something's out of place or something, or you're misunderstanding something about how it's set up heh..orrr..the dlink router is actually a modem itself, and if that's the case then maybe you don't actually need the motorola modem, I dunno..
In further detail, it looks like you might have a similar setup to what I have, because I have a modem, a router, and a switch, and several computers in my house that are plugged into the switch. But say "NIU" is actually your ISP that comes in from the wall...if that's the case, then I think it might should be set up like this:
NIU -> modem -> router -> switch -> your computer(s)
So, it should actually be like... "between the switch and the modem, there should be a router", if you have a switch, then plug the router into the modem, and plug one of the ports on the switch into one of the ports on the router..then, plug the computers in your house into the switch. Then the router will use the switch to host more computers, that might work better..try that.