Short Distance NLOS in an apartment building

I am currently trying to setup file sharing between myself and a friends apartment in the same building as my apartment (HD streaming ~ 15-20Mbps). His apartment is located 2 apartment over, down a floor, and across the hall, overall about 150 feet. Although the distance is not too far, it is obviously not line of sight. I have tried several methods to get a connection across such as EOP (Ethernet over power-lines), MoCA, and now WiFi. I have two WRT54G's running DD-WRT each with 30$ 18dBi Yagi antennas I purchased from Amazon. These antennas appear to make hardly any difference over the stock antennas, even when in line of sight (directly down the hallway). Do you think that these may just be junk antennas or am I going about this the wrong way entirely. Is it possible there is simply too much interference and attenuation? Is a directional antenna the wrong hardware to use in this situation due to multipathing?

I was considering returning these antennas and purchasing 24dBi Parabolic Dish antennas although I am starting to think that this won't help my situation any.

Another thing I was considering was purchasing 900Mhz access points from Ubiquiti to help penetrate the walls and escape all of the 2.4Ghz clutter. Will this help any or am I just wasting time?

Hopefully someone has a suggestion or some good reading material I may have missed.

Thanks
Ryan