Move the access point a little closer to the HDTV. Now turn on router and modem first. Let them sync up for a few minutes. Then, try HDTV again with wifi connection.
If that doesn’t work, try a wired (ethernet) connection before trying wifi again.
Third try is to factory reset tv, or possibly trying another frequency band or channel on your router.
my sister have a SAMSUNG Smart TV UA32ES6220, but when i tried to detect SSIDs, it keep disappears
Youtube Link: https://youtu.be/zRieFiXJrbw

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