If none of the above methods work for you, you can use a few additional options unique to your television brand.
Samsung TV not connecting to Wi-Fi
Troubleshoot using the Network Status screen. Try the self-diagnosis feature of the Samsung TV. Ensure that the distance between the modem or router and the TV is within 10.5 feet with no obstacles.
Sony TV not connecting to Wi-Fi
Power reset your TV by unplugging the power source and waiting for 60 seconds. If an external USB device is connected to the TV, disconnect it first.
LG TV not connecting to Wi-Fi
Turn off Quick Start. Turn off LG's Simplink feature. Remove any USB memories attached to your TV. Do a smartphone hotspot test.