One of these should hopefully help you as you are among many others experiencing the same issue.
First try to reset your TV.
Open the Settings menu. Go to General. Select Reset. When asked for a PIN, enter your PIN or use the default PIN 0000. Click the Reset button. Click OK. In some Samsung smart TV models, there is a different way. Go to the Settings menu. Choose Support. Select Self Diagnosis. Click Reset.
Smart Hub Reset.
On the Settings menu, go to Support. Select Device care. Click Self-Diagnosis. Select Reset Smart Hub. Enter your PIN or the default PIN 0000. Click OK.
If these fail then try using a different Samsung Account.
Press the Menu button on your Samsung smart TV remote. Select System. Choose Samsung Account. Click the option on how you want to create a new account.
Last but not least, Change the DNS Settings.
On your remote, press the Menu button. Go to Settings.Select Network. Choose Network Settings. Select Start. Choose IP Settings. Click DNS settings. Select Enter manually. Click OK. Enter 8888. Click OK.
Again. I hope this helps.