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Not getting 802.11n or 'ac' speeds on my new 'ac' devices

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nc8q's picture
Not getting 802.11n or 'ac' speeds on my new 'ac' devices

Neither Stable nor Nightly 20230709 attempts 802.11n nor 802.11ac speeds. Using Nightly 20230709 My -nD to nD devices are capable of 130/144 TxMbps link speed. My -ac to -ac and -nD to -ac only attempt 802.11g speeds!

I was hoping to see a MCS8 156/173.3 link between my -ac devices. Especially, I was not expecting to be reduced to 802.11g, 54 TxMbps.

See edited.

73, Chuck

nc8q's picture
Still only getting 802.11g speed on my SXTsq-5ac device.
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w6bi's picture
Modulation rate

Chuck, TxMbps is not a link speed - it's (mostly) just modulation rate.  It looks like the link is running MCS 13 which would be 115.6 Mbps, but since we're running 10 MHz bw, it'd be half that or 57.8 Mbps.  I believe the displayed AREDN TxMbps is adjusted for successful packet completion, which in this case is 93%  (54/57.8)

Orv  W6BI

nc8q's picture
Hi, Orv:

Hi, Orv:

As advertised in "See edited":

nD to ac link:
root@NC8Q-LHG5-175:~# cat /sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/74:4d:28:92:be:26/rc_stats

              best    ____________rate__________    ____statistics___    _____last____    ______sum-of________
mode guard #  rate   [name   idx airtime  max_tp]  [avg(tp) avg(prob)]  [retry|suc|att]  [#success | #attempts]
OFDM       1           6.0M  272    1640     5.2       5.2     100.0       3     0 0             0   0        
OFDM       1           9.0M  273    1104     7.7       7.7     100.0       4     0 0             1   1        
OFDM       1          12.0M  274     836    10.0      10.0     100.0       4     0 0             0   0        
OFDM       1          18.0M  275     568    14.3      14.3     100.0       5     0 0             0   0        
OFDM       1    D     24.0M  276     436    18.1      18.1     100.0       5     0 0             1   1        
OFDM       1   C P    36.0M  277     300    24.9      24.9     100.0       5     0 0             1   1        
OFDM       1  B       48.0M  278     236    30.4      30.4     100.0       5     0 0            28   28       
OFDM       1 A        54.0M  279     212    33.0      33.0     100.0       5     1 1           354   359      

Total packet count::    ideal 375      lookaround 10
Average # of aggregated frames per A-MPDU: 1.0

802.11n MCSs are not attempted, only 802.11g speeds are attempted.
It seems to me that my 802.11n device (RB-LHG-HP5nd) thinks that my RB-SXTsq-5ac device is an 802.11g device.
Why else would only be testing and linking at 802.11g MCSs?

Also note that the LQ and NLQ are all 100%, so there is no multiplication with values < 1.0 happening.


73, Chuck

w6bi's picture

Interesting!  Have you tried reloading the software?

nc8q's picture
TxMbps 54: Multiple firmware versions =>, 202308??

"Have you tried reloading the software?"

TxMbps 54: Multiple firmware versions =>, 202308??
I tried to load iperfspeed_0.8, but is seems to be failing to load on the Nightly.
Now, even my GL iNet AR300M16 is doing 54 Mbps with the Nightly.
73, Chuck


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nc8q's picture
is my RB SXTsqg-5ac advertising 802.11ac speeds?

root@NC8Q-5ac:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/64:d1:54:9c:85:af# ls
addba aid delba he_capa peer_debug_trigger tx_filtered
addba_resp airtime driver_buffered_tids ht_capa peer_ps_state vht_capa
agg_status aql dump_tid_stats last_seq_ctrl rx_duplicates
aggr_mode aqm flags num_ps_buf_frames rx_fragments
root@NC8Q-5ac:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/64:d1:54:9c:85:af# cat vht_capa
VHT not supported

root@NC8Q-5ac:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/64:d1:54:9c:85:af# cat ht_capa
ht not supported
root@NC8Q-5ac:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/64:d1:54:9c:85:af# cat he_capa
HE not supported

I think
'ht' is 802.11n MCSs,
'vht' is 802.11ac MCSs,
'he' is 802.11ax MCSs.

My RB-LHG-5nD indicates its 'ht' is supported:
root@NC8Q-5nd-0:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/74:4d:28:92:be:26# ls
agg_status aqm he_capa node_aggr rc_stats rx_fragments
aid driver_buffered_tids ht_capa node_recv rc_stats_csv tx_filtered
airtime flags last_seq_ctrl num_ps_buf_frames rx_duplicates vht_capa
root@NC8Q-5nd-0:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/74:4d:28:92:be:26# cat vht_capa
VHT not supported#
root@NC8Q-5nd-0:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/74:4d:28:92:be:26 cat ht_capa
ht supported
cap: 0x19ef
SM Power Save disabled
RX STBC 1-stream
Max AMSDU length: 7935 bytes
ampdu factor/density: 3/6
MCS mask: ff ff 00 00 00 00 00 00 00 00
MCS tx params: 1

root@NC8Q-5nd-0:/sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/74:4d:28:92:be:26# cat he_capa
HE not supported

Is this the reason my 802.11n devices think my 802.11ac device is only capable of 802.11g MCSs?

73, Chuck

nc8q's picture
TxMbps is not a link speed - it's (mostly) just modulation rate

Hi, Orv:
Yes, TxMbps is is a data speed, not data throughput speed.
TxMbps indicates the link speed (MCS) less retries (if any).
iperfspeed would indicate throughput (TxMpbs)*(LQ/100)*(NLQ/100)-overhead(FEC,...)
These are half-duplex radio links so throughput can only approach MCS speed selected.

I am looking at rc_stats and wondering if my new 'ac' device broadcasts that it can do 802.11 encoding.

73, Chuck


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