100 feet is pushing it these days, while the specs say it should reach there's a lot of interference from competing signals now. Have you tried moving your router? You'd want it against the wall closest to your neighbor. Raising it higher can also help. For example, on top of a bookshelf. And avoid placing it behind signal obstacles, anything metal, thick glass, or electrically "noisy" appliances like fluorescent bulbs, dimmer switches, microwaves, etc.