Device on SSID A kills traffic on SSID B

I have a strange issue with Netgear R7800 running OpenWrt 19.07.2.

On 5G (channel 44) i have 2 SSIDs, SSID A (main subnet) and SSID B (guest subnet). My business laptop (win10) is connected to SSID B and my personal laptop (linux) to SSID A.

The win10 laptop has no issues, VPN is stable and fast but the connections on the linux laptop drop packets, ssh connections stall for quite some time, 10-30s. The win10 laptop does not generate a lot of traffic, so it's not a bndwitdth issue.

if i put one laptop into 2G or both laptops in the same 5G SSID, doesn't matter which one, the issue is gone.

Has anyone seen somethin similar? Any idea what that could be? There are no other APs on channel 44 and i don't see any wlan messages on linux.

Does the connection on the Linux laptop work properly when the Windows laptop is off?

Yes, I have the issue only if the windows laptop is on.

This is weird... are there any messages in the router's logs?

  • Are these SSID's connected to different Interfaces/networks?
  • And if so, they have separate IP ranges?
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No messages in the router logs or linux laptop logs. and yes, it's weird.

yes, the SSIDs are connected to different interfaces with separate IP ranges.

the win10 laptop is connected to guest wifi, the linux laptop to main wifi, both are separated by interfaces, networks, firewall zones, etc.

It doesn't seem to be consistent, this morning i put the win10 on guest wifi again and it works without any issues, at least for now.

i noticed the win10 laptop is always connected with full rx/tx speed

866.7 Mbit/s, 80 MHz, VHT-MCS 9, VHT-NSS 2, Short GI
866.7 Mbit/s, 80 MHz, VHT-MCS 9, VHT-NSS 2, Short GI

while all other devices are stepping down like

780.0 Mbit/s, 80 MHz, VHT-MCS 8, VHT-NSS 2, Short GI
260.0 Mbit/s, 80 MHz, VHT-MCS 5, VHT-NSS 1, Short GI

if they don't need full bandwidth. Unfortunately i cannot change wlan settings on the win10...

That attests to the clear channel, not use of any live bandwidth. This is the theoretical bandwidth of the WiFi PHY, if you will...

Does your Windows 10 device have WiFi Sense enabled?

yes, but they change for all other devices except windows10, win10 never changes, it's always "866.7 Mbit/s, 80 MHz, VHT-MCS 9, VHT-NSS 2, Short GI" for RX/TX.

my win10 1909 has no wifi sense.