I do not have an M4 (I have an X50) but if you look at my posting above, you will see that I went into the Deco app on my phone and set the QoS to 999 Bps up and 999 down rather than the recommended...

@TP-Link I have a Deco X50 system set as Router connected to a Virginmedia Hub4 with 1GBps down and 100MBps up contract. In the Deco app I have QoS enabled. If I set it to 1000MBps the speed test...