That sounds like a poor line. Your drop outs could be due to your line.
I got an Asus N66U router, brobably more than you want to pay, but its Wi-Fi is so good, I was able to get rid of the repeater I had to use with the last one. Not only that, but the furthest computer gets a much better signal now too.
My parents are close to their exchange - not as close as you are to yours. They sync at a rock solid 8Mb - the max, and their line is so good it has an SNRM of (IIRC) about 20dB; at least it is well above 6.
Stress - the condition brought about by having to resist the temptation to beat the living daylights out of someone who richly deserves it.