Router+Switch and DHCP problems

Holy crap he's asking a question. Damn right I am. It's 2:30am and I've spent the last few hours searching for answers to this but I can't get anything concrete - and now is not the time to take a crash course in crazy networking stuff.

So, modem connected to router. Got a wireless laptop and a wired box connected to the router and they're working fine. Got a switch: Netgear GS108T(v2). Connected it to the router and that's fine so far. It has an IP address, I can access it from the laptop, blah blah blah.

Now I've added a box behind the switch and that's not fine. It's stuck on trying to get an address from the router: I see the request get sent, the router sees and responds, but the offer never makes it back to the box. I suspect this is a symptom of larger problems which I don't know about.

What's wrong, what should I do to fix it, and/or what else do you need to know?
My best guess was blindly "tagging" and untagging ports all over the place, but that hasn't worked.

It looks like that router has DHCP filtering that will block a DHCP server's reply unless the port the request comes in on has been authorized to receive DHCP requests.

See page 72:
ftp://downloads.netgear.com/files/G..._SWA_5Nov10.pdf

That's my initial guess.

Figures it was something easy


Okay, that works - has a lease and all - but I (still) can't access anything else. Not the switch, router, or another computer on the network.
192.168.1.1 is the router; the computer knows the MAC address, the switch knows which port has it, but from there I'm not sure what's happening.

[edit] Found it. That mass tagging I did earlier? Seems I didn't fully undo that. Sometime I'll have to learn what all it means, but for now I know that I shouldn't muck around with it because my track record has been Screwing Things Up 2, Fixing Problems 0.