@Morino 

Yes, you can have that setup. You will get the coverage, but expect to see slow speeds when connecting to the extender further out because of how data is handed from one extender to another.

I would factory default both extenders, then use Tether to set up the first one to the router, and set the network names to be different. When that is done, set up the second extender using the Tether app as well.

Here is a FAQ showing how to use our Tether app: https://www.tp-link.com/us/support/faq/1971/

Having all names being the same makes it hard to know what device is connecting to what and can cause devices to keep jumping to different nodes.

I would have something like:

Router:

mywifi

mywifi-5G

Extender 1:

mywifi-ext

mywifi-5G-ext

Extender 2:

mywifi-ext2

mywifi-5G-ext2