Tech9
Part of the Furniture
I am running AC88U with 386.3 Traditional QoS does not work infact it slows my connection down to 5 meg download
I currently play with an older RT-AC1900P with exactly the same BCM4709C0 1.4GHz CPU as in your RT-AC88U. With Traditional QoS enabled (it disables NAT acceleration) the router can do >200Mbps no problem. Something else is wrong with your router or firmware. Mine is running Asuswrt 386_43129.