Just set up this AX53 and the 5G wifi speeds are markedly slower than my old AC router

wired speeds:

wireless:

all wifi clients suffer from approx the same speed - 3-400 mbps. have tested with 2 other laptops and 2 phones, all support wifi 6.

devices are tested approx 1 foot away from router. nothing is causing interference or using the connection. 2.4 and 5 ghz SSIDs are split, devices are connected to the correct network

channel widths are all max, open channels are being used. nothing changes if i disable ax.

previous router (virgin superhub 4) was getting approx 800 mbps wifi throughput under the same circumstances

is there anything i'm missing or this router fundamentally bad?