@FHR 

Hi, Thank you very much for the feedback.

"Deco in WiFi-Router mode...

Best is 10Mbps

QoS is off, SIP is off, UPNP is off

Deco in Access Point Mode
(obvious you then lose the ability to reserve addresses and priority and more. )

Best is 30Mbps

"

Are these speedtest results from the main Deco PX50, or the satellite Deco PX50? WiFi or LAN connection?

Please replace a new Ethernet cable between the Zyxel router and the main Deco PX50.

When you are available, it is also suggested to set a different Deco as the main Deco: How to replace the main Deco with another Deco

Thank you very much and best regards.