Your ISP's DHCP does not function correctly Asus router

Hi. I know it has been asked before, but for some reason I cannot find my way to respond to those threads. I've had this issue back in September after power surge during lightning. When I plug modem directly to the desktop, I have internet, but when modem is plugged in to the router, the router gives this message: Your ISP's DHCP does not function correctly.

Last time I tweaked things around but afterall, resetting modem from Comcast web site couple of times worked. This time resetting on my own doesn't seem to work. No surges or outages this time, it just stopped. Calling customer service last time didn't help at all. Is it bad router or connection issue? I don't want to spend on new router and end up with the same issue... Please, any advice would be appreciated.