Can I block other signals?

You can move your AP to a different channel, and try moving your antenna positon to minimise unwanted APs signals... Guy

avalanche hath wroth:

Block? Well, you could wrap your house in aluminium foil. That should block any outside interference. Tinkering with the MAC and SSID will not do anything for interference.

I can't really tell if you're having interference problems or if you don't have sufficient signal. My guess is that since you're going through a least one floor, it might be a combination of the two. I suggest you spend some time playing with:

1. Try different channels. 1, 6, and 11 are the non-overlapping US channels. If interference, that should help.
2. Try different positions for the unspecified model Pre-N router. The vertical antennas are fine for clients that are on the same level, but don't do much for signals above and below (through floors). Try hanging it on the wall with the antennas horizontal. You can try reflectors as in:
   formatting link
   I don't know what it will do to a Pre-N signal. Also, move the access point away from any windows the are likely to be the entry point for any interference.
3. If the client radios are *NOT* Pre-N MIMO, then try a reflector or external antenna to improve signal strength.