Wireless Extenders plugged into LAN port?

[SunshineAndSnow]

I have my Telus modem in the garage in the basement.

A LAN cable runs to the main floor and also to the bedroom upstairs (3 levels).

I have one Wireless Extender on the 2nd floor, plugged into the LAN port.

The 2nd Wireless Extender is on the 3rd floor, also plugged into the LAN port.

Is only one Wireless Extender supposed to be plugged in or is it beneficial or necessary for them all to be plugged into a LAN port?

The documentation says the first Wireless Extender should be plugged into the router.  Is that necessary? 

It seems like a better solution to have one on each floor.

Thanks

[NFtoBC]

Which wireless extender? There are a number of different models.

Also, which router do you have?

[SunshineAndSnow]

It says Model DWS

White flat dish with a blue light.

[NFtoBC · Accepted solution]

They will work happily, and better if both connected by Ethernet. If necessary, you can disconnect the more distant one from Ethernet, and it will act as a mesh connected device at half the speed it currently does.