@stavrov 

Have these powerline adapters established connection to each other? If they have status lights, you can check that easily. Usually TP-Link powerline adapters are compatible with Deco mesh, unless maybe they are really old. What is model name/number of these adapters?

Also, if these powerline adapters show link between each other, test that link by connecting security camera directly to powerline adapter on 2nd floor. If it keeps streaming, the link is good, if not - powerline adapters have a problem.

Of course, for that test second powerline adapter must be connected to 3rd floor Deco.

Another option is to revisit "Ethernet link between 4th and 2th floor which is used fo TV." Even if it will take time to make that link work for Deco mesh, that would be the best option.

Othe than that, if 2nd floor Deco connects over WiFi to Main Deco on 4th floor, there is also an option to configure 2nd floor Deco to connect to 3rd floor Deco, but that may require installing beta firmware on all your Deco units. Connecting 2nd floor Deco to 3rd floor Deco should improve WiFi signal of 2nd floor Deco, but I can't tell by how much.

Before we go there, check in Deco app to which Deco is 2nd floor Deco connected: to Main Deco or to 3rd floor Deco.

  @Alexandre. 
 

hey there,

powerline adapters did not did the trick. However with some creativity and 2 switches I was able to establish a 3rd Ethernet connection, so now I have 3 floors which are completely covered.

Thank you very much for your assistance,

I'm very happy to be in the tp link community:)

regards,

stavrov