My wireless Signal Drops only at ngiht?

What exactly do you mean by "at night"? If you're talking about the evening hours from about 6 PM to 10 PM, then the most likely problem is that you're getting interference from other wireless network activity when your neighbors get home from work. You may be able to help decrease that interference by switching your network to a different channel number, but rather than just choosing a random channel, get a wifi analyzer program (NetStumbler seems to be a good, free one: a href="http://www.stumbler.net" rel="nofollow"http://www.stumbler.net/a though I haven't used it myself--or if you have a smartphone with wifi, there are several good apps for Android and iPhone). That analyzer program should show you the other networks in the neighborhood including the signal strength and channel number. Then pick a channel that has the fewest strong signals on nearby channels. The most commonly used channels are 6, 1, and 11 (in that order), so there's a good chance you might be able to use 3, 4, 7, or 8--but check using an analyzer program first, it'll save you a lot of trial and error. If that doesn't help, or if by "at night," you mean more like the middle of the night when your neighbors are probably asleep, then you may be getting interference from other sources. Common sources of interference are cordless phones and microwave ovens, but there might also be something else in or near your neighborhood that are generating the right frequency RF signals--if that's the case, there may not be anything you can do about.