How do I get my Xfinity router to recognize my TCL Smart Tvs and allow them to connect?

In the last 4-5 weeks my TCL tvs have had problems staying connected to my network. Eventually they completely disconnected and I get an error code 014.09(?). I tried to add the MAC address of the TV directly to the router but that did not work,. I have cycled, Factory reset the TV, and called TCL. They said Router needs to switch from AES to TKIP, which would remove whatever "restriction" is preventing the TVs (now 2) from connecting. Any guidance would be helpful, as Xfinity says that will/cannot adjust this setting.