I have seen some videos about the TP-link decos and going by them then it depends on things, like what is in the walls and stuff like that.
8 meters is a fair distance to be honest, should be okay through a wooden floor.
The only thing you can do is get it from somewhere that allow returns, try and see. I was thinking of getting some Decos, but decided to get a Tp link ArcherAX53 with a mesh system. I only want the mesh to put into the kitchen so I get wi-fi outside in the summer. It may not be required to get a extender as this router has a good signal outside, but we will see closer to the summer.
Maybe have a look at some you tube videos
What confuses me is the AX3000 part, that is what comes up on the config settings of my router and it is on the box. Way to confuse people TP-link
Adrian
Desktop machines Mac mini pro with macOS Ventura, also pc Ryzen powered with windows something or other.
Plusnet FTTC