Slow wireless connection on 21.02-rc3

[simmedia]

Installed openwrt 21.02-rc3 on my Xiaomi Redmi Router AC2100 and found the Wi-Fi speeds to be slow. Only one Wi-Fi device can get internet speeds above 50 Mbps even though they are in the same room. Wired connection works fine and can get the full 200 Mbps from my ISP. I also tried testing using iperf3 and found that the Wi-Fi devices can only go up to 50 Mbps. Any ideas on how to fix this issue?

[ergamus]

More details can help. I'd start by posting your wireless config (/etc/config/wireless, removing any passwords or other sensitive information). Otherwise, describe: 2,4GHz or 5, channel and channel width, 802.11w on/off, encryption type (WPA2/3), are you using the correct country code, TX power, cell density setting, WMM enabled/disabled, etc.

[simmedia]

Here's my wireless config:

config wifi-device 'radio0'
        option type 'mac80211'
        option hwmode '11g'
        option path '1e140000.pcie/pci0000:00/0000:00:01.0/0000:02:00.0'
        option channel '1'
        option country 'US'
        option cell_density '0'
        option htmode 'HT40'

config wifi-iface 'default_radio0'
        option device 'radio0'
        option network 'lan'
        option mode 'ap'
        option ssid 'xxxx'
        option encryption 'sae-mixed'
        option key 'xxxx'
        option ieee80211w '1'

config wifi-device 'radio1'
        option type 'mac80211'
        option hwmode '11a'
        option path '1e140000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0'
        option cell_density '0'
        option channel '149'
        option htmode 'VHT80'
        option country 'US'

config wifi-iface 'default_radio1'
        option device 'radio1'
        option network 'lan'
        option mode 'ap'
        option ssid 'xxxx'
        option encryption 'sae-mixed'
        option key 'xxxx'
        option skip_inactivity_poll '1'
        option ieee80211w '1'

[ergamus]

I'd set your 2,4GHz channel to 20MHz unless you're the only AP that you can detect in your area. I'd set cell density to normal (since we're not allowing legacy rates anyway). If you're not the only AP around, check which channel is the least congested and select that instead. Also, try explicitly setting your output power instead of using auto.

Try testing with WPA2 only if you haven't already, some devices act poorly when 802.11w is involved, as is required for WPA3. Since your devices CPU is a dual core MIPS CPU @ 880MHz, I'm not sure what the modified crypto in WPA3 would do to performance. I'm guessing originally the device relied on some form of hardware acceleration to achieve it's advertised speeds.

You said one device was capable of data transfer >50Mbps, which band was it using exactly? Was it authenticated via WPA2 or using WPA3? Are the poorly working devices from the same manufacturer/brand? What is the CPU usage on your devices cores when running the iPerf test, is any single core maxing out? What is the MCS index for RX/TX when your client is running the iperf test?

Maybe try disabling any sort of power saving feature on your client as well, I've seen other people report poor bandwidth behavior on certain Intel cards.

Have you noticed any strange errors or warnings relating to WiFi in your system log?

[simmedia]

Found that only the Xperia XZ Premium was capable of WPA3 and the rest weren't. Changing the wireless security to WPA2 only fixed my issue.

Thanks for your assistance.