Location is the first consideration when it comes to improving your IQrouter's range. Try placing it in a different location and see if coverage improves. If the IQrouter is at one end of the home, hidden inside a cabinet, for instance, you minimize its range. The IQrouter does not have to be right next to your modem. The closer the IQrouter is to the middle of the home the better for full house coverage.
Antenna position also affects the IQrouter's range. Try and tilt one antenna completely sideways, parallel to the floor, or angled up at 45 degrees for optimal coverage to reach a higher or lower floor. Test antennas in multiple positions to see which seems to offer the broadest range and best coverage for your needs.
The physical structure of the home, particularly in the area where you placed the router, is also a factor. Remember that every ceiling, wall, or similar partition reduces the signal and decreases the range. Walls or barriers with any kind of solid metal in them have an especially negative effect on coverage.
Microwaves, printers, and your computer monitor are all saboteurs when it comes to wireless range. These items generate electromagnetic noise and interfere with your wireless IQrouter's function. Place the IQrouter as far away as possible from all such devices.
If you have other WiFi connections available in your house and are not sure if the other devices are interfering with the IQrouter's WiFi signal you can reboot the IQrouter. On boot the IQrouter will scan for other WiFi signals and switch to the least congested channel to ensure the strongest signal.
For more details and tips see WiFi related articles here: http://evenroute.com/documentation