help with Xi6-T not connecting to household wifi

I got a new TP BE5000 wifi router to go with my Xfinity modem.  It hooked up fine and laptops hooked up with no problem.  I also show a connection from that router to my LG TV.  However, the Xfinity Xi6-T TV box shows a problem with the connection.  I've restarted the modem, router and TV box.  When restarted, my TV will give the usual welcome screen, and say Connecting to your TV experience.  But then it ends by saying "There's a problem with the connection and to check the Gateway, modem or router, etc. and 'If you've recently changed your WiFi settings, go to network settings to connect.'  But not even sure how I'd do that.  Can someone help?