Some more details about the Realtek 8821cu USB dongle.
It is a "driver less" device i.e. the Windows drivers are in "CDROM" storage like location in the hardware.
I switched the USB dongle to a multi NIC x86 router device.
The device has 2 USB 2.0 ports and 2 USB 3.0 ports.
OpenWrt 24.10.0 x86 generic
# cat /etc/os-release
.....
OPENWRT_ARCH="x86_64"
OPENWRT_RELEASE="OpenWrt 24.10.0 r28427-6df0e3d02a"
.....
Relevant snippet from /etc/usb-mode.json
"0bda:1a2b": {
"*": {
"t_vendor": 8193,
"t_product": [ 13085 ],
"mode": "StandardEject",
"msg": [ ]
}
},
With the device in an USB 3.0 port lsusb shows the device as a "DISK" i.e. the kernel does not do an auto mode switch.
# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux 6.6.73 xhci-hcd xHCI Host Controller
***Bus 001 Device 002: ID 0bda:1a2b Realtek DISK***
Bus 002 Device 001: ID 1d6b:0003 Linux 6.6.73 xhci-hcd xHCI Host Controller
Bus 002 Device 002: ID 18a5:0250 Verbatim STORE N GO
And with the device in an USB 2.0 port lsusb shows it as a NIC device i.e. the kernel does an auto mode switch
# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux 6.6.73 xhci-hcd xHCI Host Controller
***Bus 001 Device 005: ID 0bda:c811 Realtek 802.11ac NIC***
Bus 002 Device 001: ID 1d6b:0003 Linux 6.6.73 xhci-hcd xHCI Host Controller
Bus 002 Device 002: ID 18a5:0250 Verbatim STORE N GO
With the device in the USB 2.0 port, I have configured an AP SSID 'OpenWrt-rtl8821'
No matter the mode setting (screenshot below), the SSID does not show up when I scan for WiFi APs on my cell phone.
Here is the output from iw list
Wiphy phy0
wiphy index: 0
max # scan SSIDs: 4
max scan IEs length: 2243 bytes
max # sched scan SSIDs: 0
max # match sets: 0
Retry short limit: 7
Retry long limit: 4
Coverage class: 0 (up to 0m)
Device supports T-DLS.
Available Antennas: TX 0x1 RX 0x1
Configured Antennas: TX 0x1 RX 0x1
Supported interface modes:
* IBSS
* managed
* AP
* AP/VLAN
* monitor
Band 1:
Capabilities: 0x196e
HT20/HT40
SM Power Save disabled
RX HT20 SGI
RX HT40 SGI
RX STBC 1-stream
Max AMSDU length: 7935 bytes
DSSS/CCK HT40
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 2 usec (0x04)
HT Max RX data rate: 150 Mbps
HT TX/RX MCS rate indexes supported: 0-7, 32
Frequencies:
* 2412.0 MHz [1] (30.0 dBm)
* 2417.0 MHz [2] (30.0 dBm)
* 2422.0 MHz [3] (30.0 dBm)
* 2427.0 MHz [4] (30.0 dBm)
* 2432.0 MHz [5] (30.0 dBm)
* 2437.0 MHz [6] (30.0 dBm)
* 2442.0 MHz [7] (30.0 dBm)
* 2447.0 MHz [8] (30.0 dBm)
* 2452.0 MHz [9] (30.0 dBm)
* 2457.0 MHz [10] (30.0 dBm)
* 2462.0 MHz [11] (30.0 dBm)
* 2467.0 MHz [12] (disabled)
* 2472.0 MHz [13] (disabled)
* 2484.0 MHz [14] (disabled)
Band 2:
Capabilities: 0x196e
HT20/HT40
SM Power Save disabled
RX HT20 SGI
RX HT40 SGI
RX STBC 1-stream
Max AMSDU length: 7935 bytes
DSSS/CCK HT40
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 2 usec (0x04)
HT Max RX data rate: 150 Mbps
HT TX/RX MCS rate indexes supported: 0-7, 32
VHT Capabilities (0x03d07122):
Max MPDU length: 11454
Supported Channel Width: neither 160 nor 80+80
short GI (80 MHz)
SU Beamformee
MU Beamformee
+HTC-VHT
VHT RX MCS set:
1 streams: MCS 0-9
2 streams: not supported
3 streams: not supported
4 streams: not supported
5 streams: not supported
6 streams: not supported
7 streams: not supported
8 streams: not supported
VHT RX highest supported: 390 Mbps
VHT TX MCS set:
1 streams: MCS 0-9
2 streams: not supported
3 streams: not supported
4 streams: not supported
5 streams: not supported
6 streams: not supported
7 streams: not supported
8 streams: not supported
VHT TX highest supported: 390 Mbps
VHT extended NSS: not supported
Frequencies:
* 5180.0 MHz [36] (23.0 dBm)
* 5200.0 MHz [40] (23.0 dBm)
* 5220.0 MHz [44] (23.0 dBm)
* 5240.0 MHz [48] (23.0 dBm)
* 5260.0 MHz [52] (24.0 dBm) (radar detection)
* 5280.0 MHz [56] (24.0 dBm) (radar detection)
* 5300.0 MHz [60] (24.0 dBm) (radar detection)
* 5320.0 MHz [64] (24.0 dBm) (radar detection)
* 5500.0 MHz [100] (24.0 dBm) (radar detection)
* 5520.0 MHz [104] (24.0 dBm) (radar detection)
* 5540.0 MHz [108] (24.0 dBm) (radar detection)
* 5560.0 MHz [112] (24.0 dBm) (radar detection)
* 5580.0 MHz [116] (24.0 dBm) (radar detection)
* 5600.0 MHz [120] (24.0 dBm) (radar detection)
* 5620.0 MHz [124] (24.0 dBm) (radar detection)
* 5640.0 MHz [128] (24.0 dBm) (radar detection)
* 5660.0 MHz [132] (24.0 dBm) (radar detection)
* 5680.0 MHz [136] (24.0 dBm) (radar detection)
* 5700.0 MHz [140] (24.0 dBm) (radar detection)
* 5720.0 MHz [144] (24.0 dBm) (radar detection)
* 5745.0 MHz [149] (30.0 dBm)
* 5765.0 MHz [153] (30.0 dBm)
* 5785.0 MHz [157] (30.0 dBm)
* 5805.0 MHz [161] (30.0 dBm)
* 5825.0 MHz [165] (30.0 dBm)
interface combinations are not supported
HT Capability overrides:
* MCS: ff ff ff ff ff ff ff ff ff ff
* maximum A-MSDU length
* supported channel width
* short GI for 40 MHz
* max A-MPDU length exponent
* min MPDU start spacing
max # scan plans: 1
max scan plan interval: -1
max scan plan iterations: 0
Supported extended features:
* [ RRM ]: RRM
* [ SET_SCAN_DWELL ]: scan dwell setting
* [ FILS_STA ]: STA FILS (Fast Initial Link Setup)
* [ CONTROL_PORT_OVER_NL80211 ]: control port over nl80211
* [ TXQS ]: FQ-CoDel-enabled intermediate TXQs
* [ SCAN_RANDOM_SN ]: use random sequence numbers in scans
* [ CAN_REPLACE_PTK0 ]: can safely replace PTK 0 when rekeying
* [ CONTROL_PORT_NO_PREAUTH ]: disable pre-auth over nl80211 control port support
* [ DEL_IBSS_STA ]: deletion of IBSS station support
* [ SCAN_FREQ_KHZ ]: scan on kHz frequency support
* [ CONTROL_PORT_OVER_NL80211_TX_STATUS ]: tx status for nl80211 control port support
* [ POWERED_ADDR_CHANGE ]: can change MAC address while up
