Sorry, but that doesn't make sense. If it's a router problem, why would it be fixed by rebooting the phone adapter? Why is the phone perfectly good then for 1-3 weeks before these oddities start happening again. My router is permanently on an gets restarted manually about twice a year (+ power outages longer than my UPS can last).

And my router configuration has not changed in 2 years at least (i have a separate wireless access point that controls ALL other network devices).