Unable to create a virtual interface (iw dev wlanXX interface add ...)

[BERNHARD Raphaël]

I have the following USB dongle:

Bus 001 Device 005: ID 0bda:b812 Realtek Semiconductor Corp. RTL88x2bu [AC1200 Techkey]

I've been using it in 5Ghz AP mode with this driver for more than one year without any problem.

Now I need to setup my WIFI AP in both 5Ghz and 2.4Ghz.

So I followed the "standard way" to create the second virtual interface. And this fails.

$ iw dev wlan1 interface add ap1 type __ap
command failed: No such device (-19)

For information:

• since I needed to setup both bands, I added TP-Link Archer T1U dongle to start the second AP
• the virtual interface creation command works perfectly on the Archer (= wlan0)

$ uname -a
Linux pirel 5.15.0-1035-raspi 38-Ubuntu SMP PREEMPT Tue Jul 18 16:34:51 UTC 2023 armv7l armv7l armv7l GNU/Linux

$ iw phy1 info
Wiphy phy1
wiphy index: 1
max # scan SSIDs: 9
max scan IEs length: 2304 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.
Supported Ciphers:
* WEP40 (00-0f-ac:1)
* WEP104 (00-0f-ac:5)
* TKIP (00-0f-ac:2)
* CCMP-128 (00-0f-ac:4)
* CMAC (00-0f-ac:6)
* GCMP-128 (00-0f-ac:8)
* GCMP-256 (00-0f-ac:9)
* CCMP-256 (00-0f-ac:10)
* GMAC-128 (00-0f-ac:11)
* GMAC-256 (00-0f-ac:12)
* CMAC-256 (00-0f-ac:13)
Available Antennas: TX 0 RX 0
Supported interface modes:
* IBSS
* managed
* AP
* monitor
* P2P-client
* P2P-GO
Band 1:
Capabilities: 0x1963
RX LDPC
HT20/HT40
Static SM Power Save
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: 16 usec (0x07)
HT Max RX data rate: 300 Mbps
HT TX/RX MCS rate indexes supported: 0-15
Bitrates (non-HT):
* 1.0 Mbps
* 2.0 Mbps
* 5.5 Mbps
* 11.0 Mbps
* 6.0 Mbps
* 9.0 Mbps
* 12.0 Mbps
* 18.0 Mbps
* 24.0 Mbps
* 36.0 Mbps
* 48.0 Mbps
* 54.0 Mbps
Frequencies:
* 2412 MHz [1] (16.0 dBm)
* 2417 MHz [2] (16.0 dBm)
* 2422 MHz [3] (16.0 dBm)
* 2427 MHz [4] (16.0 dBm)
* 2432 MHz [5] (16.0 dBm)
* 2437 MHz [6] (16.0 dBm)
* 2442 MHz [7] (16.0 dBm)
* 2447 MHz [8] (16.0 dBm)
* 2452 MHz [9] (16.0 dBm)
* 2457 MHz [10] (16.0 dBm)
* 2462 MHz [11] (16.0 dBm)
* 2467 MHz [12] (16.0 dBm) (no IR)
* 2472 MHz [13] (16.0 dBm) (no IR)
* 2484 MHz [14] (disabled)
Band 2:
Capabilities: 0x863
RX LDPC
HT20/HT40
Static SM Power Save
RX HT20 SGI
RX HT40 SGI
No RX STBC
Max AMSDU length: 7935 bytes
No DSSS/CCK HT40
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 16 usec (0x07)
HT Max RX data rate: 300 Mbps
HT TX/RX MCS rate indexes supported: 0-15
VHT Capabilities (0x03c109b2):
Max MPDU length: 11454
Supported Channel Width: neither 160 nor 80+80
RX LDPC
short GI (80 MHz)
TX STBC
SU Beamformer
+HTC-VHT
VHT RX MCS set:
1 streams: MCS 0-9
2 streams: MCS 0-9
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: 867 Mbps
VHT TX MCS set:
1 streams: MCS 0-9
2 streams: MCS 0-9
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: 867 Mbps
Bitrates (non-HT):
* 6.0 Mbps
* 9.0 Mbps
* 12.0 Mbps
* 18.0 Mbps
* 24.0 Mbps
* 36.0 Mbps
* 48.0 Mbps
* 54.0 Mbps
Frequencies:
* 5180 MHz [36] (18.0 dBm)
* 5200 MHz [40] (18.0 dBm)
* 5220 MHz [44] (18.0 dBm)
* 5240 MHz [48] (18.0 dBm)
* 5260 MHz [52] (18.0 dBm) (radar detection)
* 5280 MHz [56] (18.0 dBm) (radar detection)
* 5300 MHz [60] (18.0 dBm) (radar detection)
* 5320 MHz [64] (18.0 dBm) (radar detection)
* 5500 MHz [100] (18.0 dBm) (radar detection)
* 5520 MHz [104] (18.0 dBm) (radar detection)
* 5540 MHz [108] (18.0 dBm) (radar detection)
* 5560 MHz [112] (18.0 dBm) (radar detection)
* 5580 MHz [116] (18.0 dBm) (radar detection)
* 5600 MHz [120] (18.0 dBm) (radar detection)
* 5620 MHz [124] (18.0 dBm) (radar detection)
* 5640 MHz [128] (18.0 dBm) (radar detection)
* 5660 MHz [132] (18.0 dBm) (radar detection)
* 5680 MHz [136] (18.0 dBm) (radar detection)
* 5700 MHz [140] (18.0 dBm) (radar detection)
* 5720 MHz [144] (disabled)
* 5745 MHz [149] (disabled)
* 5765 MHz [153] (disabled)
* 5785 MHz [157] (disabled)
* 5805 MHz [161] (disabled)
* 5825 MHz [165] (disabled)
* 5845 MHz [169] (disabled)
* 5865 MHz [173] (disabled)
* 5885 MHz [177] (disabled)
Supported commands:
* new_interface
* set_interface
* new_key
* start_ap
* new_station
* set_bss
* join_ibss
* set_pmksa
* del_pmksa
* flush_pmksa
* remain_on_channel
* frame
* set_channel
* tdls_mgmt
* tdls_oper
* connect
* disconnect
WoWLAN support:
* wake up on anything (device continues operating normally)
software interface modes (can always be added):
* monitor
interface combinations are not supported
Device supports SAE with AUTHENTICATE command
Device supports scan flush.
max # scan plans: 1
max scan plan interval: -1
max scan plan iterations: 0
Supported TX frame types:
* IBSS: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* managed: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* AP: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* AP/VLAN: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* P2P-client: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* P2P-GO: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
Supported RX frame types:
* IBSS: 0xd0
* managed: 0x40 0xb0 0xd0
* AP: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
* AP/VLAN: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
* P2P-client: 0x40 0xd0
* P2P-GO: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
Supported extended features:
* [ RRM ]: RRM

[Nick]

Hi @bernhara

I added TP-Link Archer T1U dongle to start the second AP... the virtual interface creation command works perfectly on the Archer (= wlan0)

That Archer uses a mt7610u chipset that is supported by an in-lernel Linux Wireless Standards compliant driver. So, yes, virtual interfaces are supported. Realtek out-of-kernel drivers do not support virtual interfaces.

Since I don't fully understand the exact setup you are looking for, I'll give you some general advice and then you can ask questions:

I have a wireless AP guide on the Main Menu here:

https://github.com/morrownr/USB-WiFi

See menu item 8. It does not require virtual interface.

Let me know.