Asus RT-AC88U only 1 device per radio can be enabled

This is a huge issue for me and I really need help. I used to use ddwrt and it worked fine, I could enable as much as 4 devices per radio with no issues.

But since I moved to openwrt I can only enable 1 device per radio. Sometimes it will work only the first time I enable the second device but after I disable it I can't enable it until I reboot.

Any one knows how to fix this issue?

BTW, I tried many firmware for my chip 4366c0, I even tried the original asus firmware, and the ddwrt firmware, but all give the same behavior, which it mean it has to do with openwrt core.

I tried all version, 22.x and 23.x, currently I am using my own build using the latest snapshot and gcc14.0.2 and binutils 2.43.1

Any help will be appreciated

Issue's called Broadcom, wifi will be sh-t in OpenWRT.

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https://openwrt.org/meta/infobox/broadcom_wifi

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the bcm4366 is fully supported https://openwrt.org/unsupported/unsupported_features

That is limitation is open source driver implementing only single function at once on all broadcom wifi. Openwrt "core" whatever that is supports multiple functions at the same time on ath?k and mt76 kinds of wifi.

iw list will tell you the allowed interface combinations for your radio(s), that's the feature set you get from hardware && firmware && driver. To the best of my knowledge, brcmfmac doesn't support more than one interface per radio, these are fullmac drivers with a rather fixed-function firmware after all (and it's not exactly great with basic functionality to begin with).

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Here is the result of iw list

Wiphy phy0
        wiphy index: 0
        max # scan SSIDs: 10
        max scan IEs length: 2048 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 roaming.
        Available Antennas: TX 0 RX 0
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * P2P-client
                 * P2P-GO
                 * P2P-device
        Band 1:
                Capabilities: 0x1022
                        HT20/HT40
                        Static SM Power Save
                        RX HT20 SGI
                        No RX STBC
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 16 usec (0x07)
                HT TX/RX MCS rate indexes supported: 0-31
                Frequencies:
                        * 2412.0 MHz [1] (20.0 dBm)
                        * 2417.0 MHz [2] (20.0 dBm)
                        * 2422.0 MHz [3] (20.0 dBm)
                        * 2427.0 MHz [4] (20.0 dBm)
                        * 2432.0 MHz [5] (20.0 dBm)
                        * 2437.0 MHz [6] (20.0 dBm)
                        * 2442.0 MHz [7] (20.0 dBm)
                        * 2447.0 MHz [8] (20.0 dBm)
                        * 2452.0 MHz [9] (20.0 dBm)
                        * 2457.0 MHz [10] (20.0 dBm)
                        * 2462.0 MHz [11] (20.0 dBm)
                        * 2467.0 MHz [12] (20.0 dBm)
                        * 2472.0 MHz [13] (20.0 dBm)
                        * 2484.0 MHz [14] (disabled)
        valid interface combinations:
                 * #{ managed } <= 1, #{ P2P-device } <= 1, #{ P2P-client, P2P-GO } <= 1,
                   total <= 3, #channels <= 1
                 * #{ managed } <= 1, #{ AP } <= 1, #{ P2P-client } <= 1, #{ P2P-device } <= 1,
                   total <= 4, #channels <= 1
                 * #{ AP } <= 4,
                   total <= 4, #channels <= 1, STA/AP BI must match
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Supported extended features:
                * [ CQM_RSSI_LIST ]: multiple CQM_RSSI_THOLD records
Wiphy phy1
        wiphy index: 1
        max # scan SSIDs: 10
        max scan IEs length: 2048 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 roaming.
        Available Antennas: TX 0 RX 0
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * P2P-client
                 * P2P-GO
                 * P2P-device
        Band 2:
                Capabilities: 0x1062
                        HT20/HT40
                        Static SM Power Save
                        RX HT20 SGI
                        RX HT40 SGI
                        No RX STBC
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 16 usec (0x07)
                HT TX/RX MCS rate indexes supported: 0-31
                VHT Capabilities (0x0c1b4064):
                        Max MPDU length: 3895
                        Supported Channel Width: 160 MHz
                        short GI (80 MHz)
                        short GI (160/80+80 MHz)
                        MU Beamformer
                        MU Beamformee
                VHT RX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: MCS 0-9
                        4 streams: MCS 0-9
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT RX highest supported: 0 Mbps
                VHT TX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: MCS 0-9
                        4 streams: MCS 0-9
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT TX highest supported: 0 Mbps
                VHT extended NSS: not supported
                Frequencies:
                        * 5170.0 MHz [34] (20.0 dBm)
                        * 5180.0 MHz [36] (20.0 dBm)
                        * 5190.0 MHz [38] (20.0 dBm)
                        * 5200.0 MHz [40] (20.0 dBm)
                        * 5210.0 MHz [42] (20.0 dBm)
                        * 5220.0 MHz [44] (20.0 dBm)
                        * 5230.0 MHz [46] (20.0 dBm)
                        * 5240.0 MHz [48] (20.0 dBm)
                        * 5260.0 MHz [52] (20.0 dBm) (radar detection)
                        * 5280.0 MHz [56] (20.0 dBm) (radar detection)
                        * 5300.0 MHz [60] (20.0 dBm) (radar detection)
                        * 5320.0 MHz [64] (20.0 dBm) (radar detection)
                        * 5500.0 MHz [100] (20.0 dBm) (radar detection)
                        * 5520.0 MHz [104] (20.0 dBm) (radar detection)
                        * 5540.0 MHz [108] (20.0 dBm) (radar detection)
                        * 5560.0 MHz [112] (20.0 dBm) (radar detection)
                        * 5580.0 MHz [116] (20.0 dBm) (radar detection)
                        * 5600.0 MHz [120] (20.0 dBm) (radar detection)
                        * 5620.0 MHz [124] (20.0 dBm) (radar detection)
                        * 5640.0 MHz [128] (20.0 dBm) (radar detection)
                        * 5660.0 MHz [132] (20.0 dBm) (radar detection)
                        * 5680.0 MHz [136] (20.0 dBm) (radar detection)
                        * 5700.0 MHz [140] (20.0 dBm) (radar detection)
                        * 5720.0 MHz [144] (13.0 dBm) (radar detection)
                        * 5745.0 MHz [149] (13.0 dBm)
                        * 5765.0 MHz [153] (13.0 dBm)
                        * 5785.0 MHz [157] (13.0 dBm)
                        * 5805.0 MHz [161] (13.0 dBm)
                        * 5825.0 MHz [165] (13.0 dBm)
        valid interface combinations:
                 * #{ managed } <= 1, #{ P2P-device } <= 1, #{ P2P-client, P2P-GO } <= 1,
                   total <= 3, #channels <= 1
                 * #{ managed } <= 1, #{ AP } <= 1, #{ P2P-client } <= 1, #{ P2P-device } <= 1,
                   total <= 4, #channels <= 1
                 * #{ AP } <= 4,
                   total <= 4, #channels <= 1, STA/AP BI must match
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Supported extended features:
                * [ CQM_RSSI_LIST ]: multiple CQM_RSSI_THOLD records
                * [ DFS_OFFLOAD ]: DFS offload

The Asus RT-AC88U is 4x4 should easily enable 2 devices per radio. But why it can do it upon reboot, but not after disabling the second device. That is nothing to do with the driver. It is something to do with the core?

The scan or channel survey is "managed" aka client, once that is engeged the multi-ap support disappears? At least so tells the combination list.

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Just curious why did you move away from DDWRT if it was functioning the way you wanted?
(I use and administer a lot of Broadcom Northstar routers (R7000, AC68U, EA6900) which run DDWRT, these old routers are still reliable and have great LAN<>WAN through put with the proprietary Broadcom hardware offload)

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