@Archundias  I have two C80 at home as of now configured in easymesh via eth. backhaul and it works perfect for last 3CWs , just ordered 3rd to extend the coverage even more.. 

I got myself tricked to eth backhaul and easymesh support on tp-links claims to support easymesh - but dont get tricked - most of the devices has a mark "planned" which means that the feature is planned in future, but with no guarantee - on my side translated: "most of the devices dont get it ever". After I realized my freshly installed AX73s waits for such fw for more than 15months I returned my freshly bought pair of AX73(s) and I bought cheap pair of C80 which does not have wifi6, but it supports easymesh and eth. backhaul already - for my purpose it is good enough (not to mention it is 3 times cheaper per device).

From wifi6 range - AX72 got the support recently - if you need wifi6 .. try AX72 (not pro version probably)

check this thread:

https://community.tp-link.com/en/home/forum/topic/593722

  @Czmazel Just added my satellite and via ethernet looks like I´m capped to 100 Mb when my internet connection is 500 Mb. Connecting directly to the C80 acting as router I get higher speeds both via WIFI and ethernet. One thing I noticed though is that my satellite does not get the latest firmware. I was able to update it to 1.12.10 Build 230208 Rel.38878n(5553) instead of 1.13.1 Build 230609 Rel.32076n(5553) that I got in my main router. 

Do you get full speeds on your satellites?

  @Archundias just got new expansion unit, it refused to get 1.13.x too .. i believe it is due to bugs found check here: (new FW is comming this week)

https://community.tp-link.com/en/home/forum/topic/615066?replyId=1242704

I updated mine manually, but I expect udate later on.

If in doubts, start new thread with your concern (in fact it is of my interrest too .. )

did not tried the speed yet. Not at home now.

  @Czmazel on eth i have 300Mb/s + too maybe check the port modes .. maybe instead auto negotiation set 1000Mb/s full duplex right away ... I have auto and it is fine .. isnt your NIC 100Mb/s only?

  @Czmazel Thanks for your suggestions! Did some tests early in the morning and ended up manually upgrading the firmware in my satellite. Now both with the same firmware version... On WIFI I tried 2 laptops (both connected to 5Ghz) and my phone (it will only connect to 2.4Ghz) and they all go up to 95 Mbps.

On ethernet... I think I´ve found a defective cable, which of course, is the longest and most complicated to replace as it goes through the walls. For some reason it was slowing down the rest of my ethernet cables despite all ports were showing as full duplex 1000 Mbps. Now that cable is unplugged and ethernet works as expected.

I´ll be doing some tests with my wife´s Iphone later today and see what results I get. 

Thank you!

  @Archundias 

I'm not using the same router as you but what I am using are 

Ax72 as main router and 2 c6 routers as access points hard wired into the WLAN socket leaving the lan sockets free. 

1 in my man cave that I have 2 tp link cameras hard wired to down the bottom of my garden that are working and showing that they are hard wired. 

And the other c6 at the very end of my house where the WiFi just can't get to as its 2 floors away and a number of floors and brick walls in the way. 

Unless the model you plan to use don't support it then I'm sure they should work in that manner