Vizio Tv Connection Issues with Home Internet

I have a 3 year old Vizio and was able to connect to the 5G network no problem. Initially, though, I forgot both my DirecTV streaming box and my Roku stick both need their own separate connection to the network. Once I took care of that everything worked fine. I did have to create a separate 2.4G network on the gateway to use for my HP printer and my air conditioner before I could get them connected, but that solution worked perfectly on the first try as well. A couple of things I'll mention, though you may already be aware - make sure you are using the WiFi network password, not the provided admin password printed on the gateway device. Secondly, make sure you go to advanced settings in network management and for each network manually select 5G or 2.4G. The auto detection feature does not seem to work very well. 
One last thought. We recently had a brief power outage in our area. When everything came back up, I had to do a reset on the gateway before anything would connect again, so that's another possible tactic to try. Hope you get sorted out.