@Elbetosan 

I had once similar error message for Android set-top box connected to one of my not smart TVs. I had to power off/on everything together: Decos (Main M9, Satellite M9, Satellite M5), ISP router/modem and set-top box to get rid of it. Just bouncing Decos didn't help, just bouncing set-top box didn't work.

If you want to try, this is the order of powering off/on for your equipment:

1. Power off all Decos. Satellite Decos first, Main Deco last.

2. Power off ISP router/modem.

3. Reboot Smart TV. It should have Reboot option, usually under About, but if not - unplug it from power outlet for 10-15 seconds and plug it back.

4. Power on ISP router/modem. Wait till it is fully operational.

5. Power on Main Deco. Wait till its light goes green.

6. At this point, if Samsung TV hasn't connected to Main Deco on its own, make it to and check if error message gone. The success would be to see Samsung TV connected (Active) in Deco app and when you open screen with its detailed info - have IP address, MAC address and Connection Type properly shown there.

7. Power on Satellite Decos.

I can't guarantee it will definitely work, but it worked for me in similar situation. 

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On a side node, if I am not mistaken your Samsung TV model has Ethernet port. If it does, I strongly recommend connecting your TV to Main Deco by Ethernet cable.

If I to share photo of my TV and other electronics under it, the picture will look almost as yours, except it'll be Sony. Main Deco is right beside it. I turned off WiFi in Sony TV and use Ethernet cable to connect TV to second Main Deco port. If you have both ports in use, you may need to get additional gigabit switch, but it will be worth it. 

For streaming on big screen TV, wired always beats wireless.