Many folks have run into the same issue that I have in the past. The cheep commercial networking routers and cable modems will create tons of noise on the HF bands. We simply created a Faraday Cage and placed all the gear inside and mounted it under the house. The network gear consists of 1 Cable Modem, 1 Netgear router and 1 Airlink wireless router configured as a glorified gateway.
http://www.kb7tbt.com/pix/faradaycage These photos are of my friend Sean KE7CDE working on the Faraday Cage and Ground. James KB7TBT www.kb7tbt.com www.ne4ga.org www.myspace.com/kb7tbt