I started having same issues when I switched to Xfinity from AT&T. I just talked to TCL support and they suggested calling Comcast to have the router setting changed from AES to TKIB and disable MAC filtering. I spent 98 minutes on the line with Comcast. Tech support referred me to "escalation dept" which after 45 said they could not make changes to the router from "their end" (which I have no idea what it means). Then they would switch me to "gateway support dept." But after 15 minutes the agent said he could not get a hold of them and someone from that dept. would call me in about an hour! I am not holding my breath.