I bought 1 set TP link Archer Air, but where my office is (PC) its not too stable network and often lagging and falling out.

I dont have a wired connection to the office, but to the room next by. Hence i bought a 2nd Archer Air Router and connected as shown in the figure (blue). All the green boxes are bought as part of a set (1x router + 2x extenders)

1) My PC connects wirelessly to "Router #1" set even if the distance is just a few meters 

to "Router #2". 

2) How can i be sure this works? and to my intentions, which is to have the PC connected to Router #2

3) I am struggeling with Extender #2 (which is in the same room as the PC, only shows "red" even if

its just 3-4m to the Archer Router #2, with tiny tiny walls.  

I suspects it does not communicate with Archer router #2, but tried to communicate with Router #1

I believe you understand what i want to acheive, please let me know if i can do any checks, tips or different configurations.

thanks in advance