HI,

I bought 3 tp-link Deco X20 yesterday.

I can link the main Deco to the modem via Ethernet and link the other two satellite Deco to the main Deco via wireless.

However i am not able to connect to my desktop / laptop via Ethernet to my main Deco.

I can connect the same laptop via Ethernet to both of my satellite Deco though.

This is contradict with the FAQ quoted below in your website.

Can you please advise how to resolve this?

quote

https://www.tp-link.com/my/support/faq/1794/

Q9: Can I use one Ethernet port on the Deco for Ethernet backhaul and the other to connect a computer?

Yes.

Note: On the main Deco, one Ethernet port should connect to the modem/router to get internet, the other Ethernet port can be used for Ethernet backhaul, or connect to a computer.
unquote