Can't explain it, but if you are saying you can solve the problem by taking the router out how can the site be blocked?
Doesn't make sense for the site to be blocked for 15mins every, just from a logistical point of view seems to overly complicated. I would of thought if they were going to block somethnig it would stay blocked or block it for a number of hours.
Not saying there isn't an issue somewhere I'd give the news groups a try
JJ