Asus router ISP DHCP does not function properly

HI - read this forum and believe I'm having the same issue: https://forums.xfinity.com/t5/Your-Home-Network/Your-ISP-s-DHCP-is-not-functioning-properly-ASUS-router/td-p/3331178 @ComcastChe are you able to assist? I think the same response would help greatly. Thank you