My house is 3-stories high and I have no reception of the wireless router in the third floor. It is a brick-concrete construction (walls and floor slabs). The router is located in the basement or let's called first floor. I cannot route an internet cable to neither the second or the third floor. I have been reading about power line ethernet hardware but the reviews and comments that I have found are mixed and people say signals fail because of equipment connected to the power grid or even the powerline buds affect other equipments connected to the electrical system. Can an external wi-fi omni-directional antenna be connected to one of the two Linksys router antenna outputs to extend the coverage of the router without affecting the router's performance? I was planning on buying one of those omni-directional antennas with approx. 12 or better dBi gain which consist of a straight 90 cms rod locating it outdoors at the second floor level with straight in-line view to the third floor windows. Will it work? Can the router work with one external antenna and one little 8" long rabbit-ear like antenna?