ASUS RT-AX82U cuts download speed after few minutes on WIFI 5ghz

[lukkil]

Hi everyone,
I have changed my router from ZTE T5400 to ASUS RT-AX82U

Asus configured in AP MODE conected by wire to my second ZTE T5400 (main router)
WLAN card in the laptop is the INTEL AX210 160mhz, connection is estabilished at 2400/2400Mbs

The problem is poor intenet speed on 5ghz WLAN connection - after starting the router (or rebooting) the speed is fine and i get approx ~750Mbps. After few minutes when i run the speed test again it drops down to max 500-550Mbps.
The speed on the LAN connection from ASUS is OK - approx 750Mbps

Before i have changed the router, speeds on the ZTE T5400 were always over 700Mbps, so IMO it's some kind issue with the ASUS wlan connection.

Any advices?

I have tested ASUS on both available firmwares but nothing changed.
Changing channels on ASUS nothing chaned at all.

Thanks in advance.

 

[degrub]

Are you sure it connected to the ASUS AP and not the ZTE at lower signal level ?
BTW, if you are testing for local WIFI/LAN bandwidth, you should use something like iPERF V2 for windows and V3 for linux.

 

[lukkil]

For sure connected to Asus AP

ZTE is placed at the second floor...

I just test the Internet speed on speedtest by ookla and as i said before:

Download speed on ASUS AP over WLAN 5Gghz is only 500-550Mbps, upload speed is ok and its the same as ZTE ( approx 150Mbps).

TOPOLOGY of my network:

ZTE MC889 ODU (in Bridge Mode)-------LAN------> ZTE T5400 IDU (as main router on the second floor) -------LAN-----------> ASUS RT-AX82U (in AP Mode)

Speedtest by ookla:

ZTE T5400:
Wifi 5ghz ~780Mbps
LAN: ~780Mbps

ASUS:
Wifi 5ghz AX 160mhz ~550Mbps
LAN: ~780Mbps

 

[degrub]

One thing to try - turn off DFS channels, restrict channel width to 80, turn off AUTO channel, reduce Tx power to minimum and then add back to get coverage needed.

 

[Tech9]

Wifi 5ghz AX 160mhz ~550Mbps

Not sure why you push for 160MHz and DFS when 2-stream AX client at 80MHz wide channel can reach 850Mbps.

reduce Tx power to minimum

No, this one on Asus routers will limit the radio to single stream. Asus calls it Power Saving. I know... don't ask me.

 

[OzarkEdge]

ASUS:
Wifi 5ghz AX 160mhz ~550Mbps
LAN: ~780Mbps

Have you tried disabling 160MHz and configuring/testing 80MHz bandwidth and a non-DFS control channel?

OE

 

[lukkil]

Hello,
yes, have already tested at 80mhz and non-DFS control channel and few manual channels - nothing changed at all :/

 

[Tech9]

Are you testing with single client only? What is the RSSI level to this client?

Your ZTE T5400 units are Qualcomm hardware with 7dBi antennas. No wonder if they perform better.

 

[lukkil]

yes, testing on one client only
but IMO its not the client problem, because before i had second ZTE T5400 in AP Mode (instead os ASUS) and everything worked fine - DOWN speeds at 5ghz were always above 700Mbps...
The strangest thing is that, after rebooting ASUS WLAN speed is OK (approx 750Mbps), but after few minutes (2-3) it drops to ~550Mbps

 

[degrub]

Sounds like an auto adjustment by the AP radio or the client radio. Maybe caused by low RSSI from the client TX.
You don't have beam forming on do you ?

 

[lukkil]

I'll check when I come back home.
This option should be disabled on Asus, right?

 

[lukkil]

i have 43dB RSII as on the screenshot
the second is Professional Tab from wireless settings on ASUS
should I disable those two options beamfoaming or leave enabled?

 

[degrub]

A couple things to try , one at a time -
disable beamforming
disable MIMO
reduce TX power to medium unless you have to have it on performance.

i don't remember if you need to reboot in between changes, but historically i do just to make sure the settings stuck.

 

[lukkil]

so:
Multi-User MIMO
OFDMA/802.11ax MU-MIMO
802.11ax/ac Beamforming
Universal Beamforming

change to disabled once a time, right?
And power to Balanced?

 

[degrub]

yes

quick question - was that RSSI value from a location close to the AP and with no walls between ?