Orbi RBK50: Internet speed ok if connected to the Satellite, slow if connected to the Router

Good afternoon netgear community,

i bought an Orbi RBK50 (Router+Satellite).

My configuration is this one:

- Router Arris in bridge mode provided by the internet provider (500Mbps internet speed in download, 20 Mbps in upload)

- Orbi Router connected via ethernet to the Arris

- Orbi Satellite connected via ethernet to the Orbi Router 

Last firmware for both Router and Satellite.

 

I live in a 2 levels apartment, the satellite is installed at level 1 and there aren't any other device near it. If i connect via WIFI (5Ghz) to it i'm able to reach 400-450 Mbps in download and 20 Mpbs in download.

 

The problem happens when i connect to the Orbi Router, there the internet speed seems to be very instable and on average speedtest is at 250 Mbps in download (no problem about upload speed, it's costantly at 20 Mbps). 

Orbi Router is installed in the living room, there are a few devices there: TV/Nvidia Shield/PS4/Sonos Beam and 2 One's all connected to the router via WIFI, and 1 Synology NAS/Philips Hue Bridge connected via Ethernet. I know sonosNet could create interference on the 5Ghz frequence, but i i'm not using sonosNet (The Beam is connected to the router via Wifi, and the 2 One's connected as surrounds).

There is also a microwave since the living area and kitchen are in the same room. Microwave is about 4 meters far from the Orbi router, but it is switched off so i guess it's not a problem.

 

I tried to:

- factory reset the router/satellite

- enable/disable daisy chain/MMOE/fast roaming/beamforming settings

- change the 5Ghz channel using the 44 (since all my devices are connected using 5ghz network), while 2.4Ghz is set at channel 11

 

At the moment i don't have any laptop with ethernet port to try to connect directly to the Orbi Router and try a speed test.

 

Any idea?

 

thanks