Howard:
You might want to go into your router settings and change your channels to a single channel instead of auto.
That's probably whats going on. Its going up and down the band for it's channel selection. Also look to see if your router requires a firmware and software update. Just to be safe, get your ISP tech guy or girl on the line to help you through it if your not comfortable playing around with your router settings.
HTH and 73:
Mike VO1AX