Your ISP's DHCP is not functioning properly
I started having this problem this evening. No changes on my end for a long time. I've only been able to get to my Asus router home page once and it displayed the DHCP not functioning error. Usually I'm unable to even hit the admin page. I've rebooted both modem and router several times. It came back for a few minutes at one point, but the connection died quickly. I called Comcast support and they said they sent a provisioning signal, but still no luck. @ComcastChe any ideas?