It sounds like the antenna is missing on the wifi router. I didn't find this pl5001a now but will look again tomorrow.
In the meantime, read http://forums.cnet.com/7723-7585_102-602528/how-to-create-a-wireless-network-for-a-large-house/?tag=contentBody;threadListing
how can I use my actiontec M1424WR as a WIFI booster or access point for my Centurylink Actiontec PK5001A? We just changed from Cable to DSL and now I only get a signal 10 ft. away from my office.