First thing I would do is see if it works wired. Then you would know for sure it's a wireless issue. If the router is as close as you say, and that's not a big deal to check. Second, I would check the Samsung Trouble Shooting Guide. Here is a link to your model. Just follow through the links to weed out your problem and get the right solution. Book mark this link, you will find it invaluable, and a great reference.
Best of luck
My smart tv isn't being very smart (just had to say it).
It's picking up the router, but when I enter my security key (or password, whatever you want to call it), it doesn't connect.
Then it shows the IP settings, and they are set to 'Obtain Automatically' but it hasn't obtained anything!
We've reset/restarted the router and the TV, multiple times. The router is directly under the TV.
The router connects to my phone, Nexus, and Laptop.
My router is Netgear WNR1000v3.
Please help, I've run out of ideas!