Comcast DHCP problems

OK in the last four days Comcast has cut my IP address lease times down to 2 hours. At at the end of that two hours there are often 3-5 minutes when I cannot get a valid lease at all.

Spoke with comcast and got the run around — “reboot everything”, “remove your router”, “unplug your toaster”, “wear a little foil hat like joaquin phoenix did in Signs”. Finally they told me it is all the router’s fault (it’s been working fine for 1 year) and that I need to sign up for their home networking option.

So I am on hold to find out what that is. Anyone have any relevant advice?

UPDATE: spoke with a much better support person at Comcast. Issue has been escalated. I continue to see lease times < 2 hours. And at every renewal, i am getting widely varying IP addresses (not so unusual) AND varying subnet masks -- anything from up to that seems odd to me. I've switched routers to no avail, also tried routerless.