Sorry to read that you are having issues with your Smart TV connecting to the wireless network.
Is it just the Smart TV that is having an issue? Do other devices connect ok?
Do you know if the Smart TV works through a wired connection if there is one available?
The router you have it does broadcast the 2.4 GHz and 5 GHz as one network. To make it easier for your devices to connect to the network, you can separate the networks with different names and passwords. To do this type in 192.168.0.1 in the address bar, sign in with the details underneath the router and on the left under Advanced go into Wireless.