Possible defective lan switch/bridge with rt-ax88u

[arpydude]

Getting only 200mb on lan ports
performed physical reset.
have 500mb internet access. wifi access yields 500mb but lan switch max's out at 200mb (single user connected during test)
switched out lan cable and port connections with same result.
clean install 388 to merlin RT-AX88U_3004_388.5_0 same results.
only new settings are passwords/ssid/username everything else is default.
Possible setting or QOS I'm unaware of? any ideas appreciated.

Update: It was initially tested with 2 different usb 1gb ethernet adapters with different drivers that yielded 200mb result.
tested with embedded ethernet adapter on pc and it gets 500mb.
Anyone have an idea adjustment on the asus router? Assuming router becuse usb network adapters have no throughput issue on any other routers or switches.

 

[Tech9]

Ports 5-8 are known to fail on this model.

 

[arpydude]

Thanks for mentioning that. ports 1-4 get 28mbs with the usb-ethernet adapater and takes very long to get served an ip address yet works fine (greater than 500mbs) with an embedded adapter. Since ports 1-4 are less than 100mbs (and not over like 200mbs was) I decided to force negotiation link with full and half duplex for 1gb resulting in no change in results.

Solution: attach any 1gb switch or bridge and problem goes away so long as you dont use other lan ports on router. Hope this helps someone else.