@DynamicDave 

The activity of devices you see in Deco app is not reported in real time and it is inaccurate. I suggest you power off PC connected to Satellite Deco, walk away from that Satellite Deco so that smartphone is not connected to it, and check Satellite Deco page again in about 10-15 minutes of that Deco staying idle. You might see some traffic in Kbps, but not 7 Mbps. Check that and if I am wrong, share another screenshot. The one that will show no devices connected to that Deco and around 7 Mbps upload speed. 

Make sure PC is fully powered off, not just in Sleep or Hibernate mode.

As for why clients have poor connection, it is because this Satellite Deco has weak link to Deco mesh. "Zwak Signaal" means "Weak signal" Google translate tells me. To improve speeds for clients, you must move that Satellite Deco closer to Main Deco, to the place where Satellite Deco reports Fair or Good for its Signal.

You haven't told what is your Internet speed, the speed that your ISP provides to you. Please share that info, and also run "Test Internet Speed" from main screen of Deco app, and share what it'll report.

Hi @Alexandre.,

I know the WiFi connection between the two is weak and can be improved; but there is a UTP cable between the two devices. So it shouldn't matter, right?

This came out of the ISP speedtest:

And this is the accesspoint without any clients (still 7 Mbps):

Thanks!
Dave

  @DynamicDave 

As far as I can tell, your Satellite Deco does not (can not) use UTP cable and connects to Main Deco by WiFi instead of Ethernet. When Satellite Deco is connected by Ethernet, this is what you should see:

I would suggest focusing on this first, because when Satellite Deco uses Ethernet, its WiFi speeds increase substantially.

There may be multiple reasons why Satellite Deco can't use Ethernet, see this FAQ document for more information: General questions about Ethernet Backhaul feature on your Deco

You can also run the following test: bring Satellite Deco to where Main Deco is, connect Satellite Deco to second port of Main Deco with short Ethernet cable of good quality. See if Satellite Deco can establish Ethernet connection to Main Deco and if that mysterious 7Mbps upload traffic drops to mere multiple Kbps.

Hi @Alexandre. 

Problem solved! The UTP cable was broken. Once I placed a new cable the speeds went back to normal.

Still strange that if the backhaul is not working and the two points are (almost) out of range it uses 7 Mbps trying to keep the connection alive.

Thanks for your answers!

Kind regards,
Dave