Hi! I'm on a 100mbps connection, with a Rev. B1/B2 and a TL-ANT2408CL (8dBi) antenna. I've recently purchased a new laptop and I've noticed some weird things happening. When in the same room with the router, in 802.11n mode, I get around 30mbps download on Speedtest.net. If I move further away (2 rooms), in spite of "Good" signal, the download speed test starts after a couple of seconds' delay, and I rarely get more than 5-10mbps on download, coupled with connection drops; my upload speed stays the same (20-25mbps)! Task Manager indicates a link speed of 39-58mbps, rarely 72mbps (instead of 150, the router's maximum). I'm on channel 11, which is clear of interference (I get 100 link speed in inSSIDer). I've read topic on other forums that blame WMM, so I disabled it, switching to g mode. This gives me download speeds of around 18-20mbps (with a 54mbps Link Speed). I have tried FW2.16, 2.17 and 2.05 and the latest dd-wrt with no results. On wired I get 95/75 speeds (with the 2.05 version; later ones cap it off at 50mbps).
I'm on PPPoE, QoS off, in Europe, Time is correct, WPS off, MTU is 1492, WPA2-PSK with AES. I get about the same results on an Android phone and on the same laptop using a USB WiFi adapter.