Netgear Nighthawk EX7500 interferes with Amazon Fire TV stick - weak signal

[scfung]

I bought this to extend the wifi signal from the router (in the sitting room) to the TV room/ office, in another room. My apartment is only 800 square feet, with one concrete wall in between.

The extender gives me tremendous speed / signal to my iMac and MacBook, somehow weakens the signal to my Amazon Fire TV stick. 

I tried unlugging the extender and re-setting it, to no avail.

The signal to my iMac went up to 63 Mps but the signal to my Fire sitck went all the way down to below 15. So much that I cannot watch anything without the picture hanging or buffering.

I have now returned the extender to the seller.

Does anyone know if an extender between the router and Fire stick can cause this issue?
Or is it just this Netgear ???
I need help urgently.
Sang

[plemans]

concrete is one of the best materials for blocking wifi. 

You might be better off if you can use powerline or moca adapters to get the signal/connection through that wall. 

[scfung]

Thank you for your concern, but the concrete wall is not the issue. When I unplugged the Nighthawk, the signal is absolutely fine. 

I was looking for advice / comment why the Netgear Nighthawk would slow donw, rather than improve the signal of the Amazon Fire TV stick.

[plemans]

The EX7500 does band steering. Is it putting the fire stick on the 2.4ghz band? its more sensitive to interference than the 5ghz band. 

[scfung]

I have done EVERYTHING! I used 2.4, 5, I switched it to my other networks including Apple Time Capsule, and amazingly the one that gives the best signal (still too low for TV) is my old BT dish! Not Vodafone (my router)!

[scfung]

Thank you for your comment. I have retruned the Nighthawk, and bought a simple 2-band Wifi Booster for half the price, and it works like a charm. I can see whether the 2.4 or th 5 is stronger and switch it around. With the nighthawk I couldnt do that.