[Bug 284409] rtwn(4) cannot DHCP on 11a network that doesn't support 6MBps rates

From: <bugzilla-noreply_at_freebsd.org>
Date: Tue, 28 Jan 2025 14:13:27 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=284409

            Bug ID: 284409
           Summary: rtwn(4) cannot DHCP on 11a network that doesn't
                    support 6MBps rates
           Product: Base System
           Version: 15.0-CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: gavin@FreeBSD.org

Hi,

I have a RTL8812AU which works fine at home, but not at work.  Symptoms are it
will wpa associate fine, but can't then DHCP.  tcpdump suggests that we're
transmitting, and we're also seeing packets sent to us, but never get a
response to the DHCP requests.  If I give it a static IP, it works.  My current
theory is that it's sending the DHCP packets at 6Mbps (seems to be confirmed
with tcpdump -y -y IEEE802_11_RADIO) but the APs at work have a minimum rate of
24Mbps so they are getting ignored.

root@omega:~ # ifconfig wlan0
wlan0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu
1500
        options=200001<RXCSUM,RXCSUM_IPV6>
        ether 40:a5:ef:xx:xx:xx
        inet6 fe80::42a5:efff:fexx:xxxx%wlan0 prefixlen 64 scopeid 0x3
        groups: wlan
        ssid eduroam channel 153 (5765 MHz 11a vht/20) bssid fc:7f:f1:xx:xx:xx
        regdomain FCC country US authmode WPA2/802.11i privacy ON
        deftxkey UNDEF AES-CCM 2:128-bit txpower 17 bmiss 7 mcastrate 6
        mgmtrate 6 scanvalid 60 ampdulimit 64k ampdudensity 4 shortgi -stbc
        -uapsd vht vht40 vht80 -vht160 -vht80p80 wme roaming MANUAL
        parent interface: rtwn0
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11ac
        status: associated
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>

root@omega:~ # ifconfig -v wlan0 list sta
ADDR               AID CHAN RATE RSSI IDLE  TXSEQ  RXSEQ CAPS FLAG        
fc:7f:f1:xx:xx:xx    9  153  39M 20.0    0     29  49168 EP   AQHVTRstrUL 
SSID<eduroam> RATES<B48,72,96,108> DSPARMS<153> TIM<050400010000> COUNTRY<GB 
36-43,23 100-110,30 149-153,14> PWRCNSTR<200100> TPCREP<23020e00> RSN<v1
mc:AES-CCMP uc:AES-CCMP km:8021X-UNSPEC+?> BSSLOAD<sta count 8, chan load 7,
aac 48> APCHANREP<class 1, chan:[36,40,44,48]> APCHANREP<class 2,
chan:[52,56,60,64]> APCHANREP<class 3,
chan:[100,104,108,112,116,120,124,128,132,136,140]> APCHANREP<class 17,
chan:[149,153,157,161,165]> UNKNOWN_ELEMID_67<430600->
RRM_ENCAPS<46057340010001> MOBILITY_DOMAIN<3603010000> HTCAP<cap 0x1ad param
0x17 mcsset[0-31] extcap 0x0 txbf 0x0 antenna 0x0> HTINFO<ctl 153, 0,4,0,0
basicmcs[]> EXTCAP<7f0a04000800000000400040> VHTCAP<cap 0x0f8b7990 rx_mcs_map
0xffaa rx_highest 0 tx_mcs_map 0xffaa tx_highest 0> VHTOPMODE<chw 0 freq0_idx 0
freq1_idx 0 basic_mcs_set 0x0000> VHTPWRENV<tx_info 0x00 pwr:[20:14.00]>
UNKNOWN_ELEMID_255<ff24-> UNKNOWN_ELEMID_255<ff07-> UNKNOWN_ELEMID_255<ff0e->
VEN<dd0e000b860103006d73646170303035> WME<qosinfo 0x80 BE[aifsn 3 cwmin 4 cwmax
10 txop 0] BK[aifsn 7 cwmin 4 cwmax 10 txop 0] VO[aifsn 2 cwmin 3 cwmax 4 txop
94] VI[aifsn 2 cwmin 2 cwmax 3 txop 47]> VEN<dd07000b860104080e>

I have pcap files I can provide if needed.

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