A:
There are three things to consider: one is how far the is the extender from the main router. The second is the signal in dbm (or bars) the extender receives from the router. Finally, the wireless protocol (N 5Ghz, N 2.4 GHz, B,G with 2x2 or 1x1 spatial streams) between the router and extender. If it's N 2.4 Ghz with 2 spatial streams and 20 MHz bandwidth, it should still give you your 18 Mbps bandwidth.