Weird speeds difference between router and Modem

[chalas]

Hello All,

A bit of background:
I recently converted a spare room to a small office in our 2bd condo. The layout of the place is 2 bds upstairs, living room, kitchen and dining room downstairs. The Modem/router Zoom 5350 (I think) is downstairs in the living room. The office is located upstairs in the opposite side from where the router is located.

My HTPC in the living room is on a Ethernet connection and I get 35 mbps DL and about 6 mbps UL. Now I have a TP-LINK TL-WN722N and a TL-WN822N that will be used in that office for 2 computers.

I was speed testing and I only get an average of 8 mbps UL and 5 mbps DL on both devices (despite one being 300 mbps). They both get great reception, TL-WN822N getting the best obviously. Yet the TL-WN722N gets a bit better speeds.

So, I purchased a stand alone Wireless router http://www.amazon.com/dp/B0062KA4VM/ref=pe_385040_30332200_pe_309540_26725410_item and speeds only went up 1 mbps. Now, when I plug the Ethernet cable from the HTPC on the router I get DL +- 10mbps, but when I plug it directly at the Modem I get DL 30+. I am confused, why is this happening?