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jheidecker
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Joined: Tue Jun 30, 2015 1:51 am

RB922UAGS-5HPacD Dual Band AP - Poor Performance

Tue Jun 30, 2015 11:35 pm

First, let me say that I have been using Mikrotik gear for years and I have never been disappointed. This is the first time I have been fully stumped.

We run a small shop and we use some CCR's as core routers and various RB's as wireless AP's. Clients are mixed windows, linux, etc. Mostly newer Intel AC cards.

We recently moved locations and replaced a RB912UAG-5HPnD + R11e-2HnD with a RB922UAGS-5HPacD (and reused the R11e) in an attempt to refresh our AP with some 802.11ac goodness.

At first glance the setup was straight forward and the clients connect just fine. Soon after though, a few users noticed that their bandwidth was inconsistent, and at most times the performance was waaay under negotiated rates.

At first I thought it was simply congestion, but the more testing we do, the more that seems unlikely. We also ruled out active interference with a scanning tool we borrowed. We're using btest for checking rates to a downstream (from the AP) router.

Sometimes, especially after first associating, we can push nearly advertised rates (200Mbit, 400Mbit) but inevitably, after a few minutes, the test goes to sub 30Mbit but the registration table still shows high rates.

Here is my wireless config:
 0  R name="2gn" mtu=1500 mac-address=4C:5E:0C:11:0E:FC arp=enabled 
      interface-type=Atheros AR9300 mode=ap-bridge ssid="radio" frequency=2447 
      band=2ghz-onlyn channel-width=20/40mhz-eC scan-list=default 
      wireless-protocol=unspecified vlan-mode=no-tag vlan-id=1 
      wds-mode=disabled wds-default-bridge=none wds-ignore-ssid=no 
      bridge-mode=enabled default-authentication=yes default-forwarding=yes 
      default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=yes 
      security-profile=radio compression=yes 

 1  R name="5gac" mtu=1500 mac-address=4C:5E:0C:60:F2:1E arp=enabled 
      interface-type=Atheros AR9888 mode=ap-bridge ssid="radio" frequency=5500 
      band=5ghz-a/n/ac channel-width=20/40/80mhz-Ceee scan-list=5500 
      wireless-protocol=any vlan-mode=no-tag vlan-id=1 wds-mode=disabled 
      wds-default-bridge=none wds-ignore-ssid=no bridge-mode=enabled 
      default-authentication=yes default-forwarding=yes default-ap-tx-limit=0 
      default-client-tx-limit=0 hide-ssid=yes security-profile=radio 
      compression=yes 
 2   name="radio" mode=dynamic-keys authentication-types=wpa2-psk 
     unicast-ciphers=aes-ccm group-ciphers=aes-ccm 
     wpa-pre-shared-key="supersecret" 
     wpa2-pre-shared-key="supersecret" 
     supplicant-identity="" eap-methods="" tls-mode=no-certificates 
     tls-certificate=none mschapv2-username="" mschapv2-password="" 
     static-algo-0=none static-key-0="" static-algo-1=none static-key-1="" 
     static-algo-2=none static-key-2="" static-algo-3=none static-key-3="" 
     static-transmit-key=key-0 static-sta-private-algo=none 
     static-sta-private-key="" radius-mac-authentication=no 
     radius-mac-accounting=no radius-eap-accounting=no interim-update=0s 
     radius-mac-format=XX:XX:XX:XX:XX:XX radius-mac-mode=as-username 
     radius-mac-caching=disabled group-key-update=5m 
     management-protection=disabled 
     management-protection-key="supersecret" 

Here is an example of the registration table:
 # INTERFACE                                 RADIO-NAME       MAC-ADDRESS       AP  SIGNAL-STRENGTH TX-RATE UPTIME              
 0 5gac                                                       AC:D1:B8:BF:B7:01 no  -52dBm@6Mbps    780M... 1h32m27s            
 1 2gn                                                        00:80:92:A0:74:2F no  -49dBm@1Mbps    52Mb... 1h32m27s            
 2 2gn                                       4C5E0C32FC0B     4C:5E:0C:32:FC:0B no  -51dBm@HT40-7   300M... 1h32m27s            
 3 2gn                                                        8C:3A:E3:47:A4:25 no  -64dBm@1Mbps    39Mb... 1h32m17s            
 4 2gn                                                        C0:EE:FB:28:EE:40 no  -66dBm@1Mbps    54Mbps  1h28m4s             
 5 5gac                                                       C4:85:08:11:15:52 no  -61dBm@HT40-7   300M... 1h17m39s            
 6 5gac                                                       D8:FC:93:A1:2D:EF no  -64dBm@6Mbps    351M... 1h2m28s             
 7 5gac                                                       D8:FC:93:12:2B:1D no  -59dBm@6Mbps    325M... 34m41s              
 8 5gac                                                       D8:FC:93:A1:FF:C2 no  -47dBm@6Mbps    325M... 34m41s              
 9 5gac                                                       D8:FC:93:71:F8:8B no  -57dBm@6Mbps    780M... 32m27s              
10 2gn                                                        54:27:1E:1A:AE:58 no  -63dBm@HT40-1   240M... 7m53s               
The CCQ is always above 50% when looking at the status of the cards, and doesn't change when the tests start to bomb.

Some things we've tried:
  • disabling either interface
    using virtual AP's instead
    all combinations of band and width (things seem more stable at lower negotiated rates, but still not fast)
    i swear, almost disabling and re-enabling all other advanced settings through trial and error
    updating to 6.30rc23 (wireless-cm2)
The debug logs do not show anything unusual and the CPU looks totally normal. I did a profile and most usage is wireless and unclassified.

All of the clients are within 50 ft of the router and there is very little in between.

I am not a wi-fi engineer, and perhaps our new location is just too noisy, but it seems very strange that we know the setup is capable of high speeds, it simply seems to be refusing to do it! I am hoping someone with more skills and knowledge can help pinpoint the issue, or at least offer some insight, so we can take next steps. Ideally it would be something with the software so we can get Mikrotik to fix :)
 
pjinkcc
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Posts: 10
Joined: Thu Aug 29, 2013 12:05 am

Re: RB922UAGS-5HPacD Dual Band AP - Poor Performance

Mon Oct 19, 2015 12:36 am

I am having the same issue where after a few minutes the bandwidth dips and stays stuck at around 35Mb. I just upgraded to a RB911G-5HPacD for a PTP bridge with an Intel 7260 wireless card. A temporary fix I discovered is rebooting the routerboard and right away you get the negotiated bandwidth. Then, after a few mins, back to low BW.

I also tested this with 802.11n only to see if it did the same thing. Yep, BUT, after about 10 seconds of running btest it will jump back up to the correct bandwidth and stay throughout a few mins worth of the full bandwidth.

I tried disabling the intel 7260 and reconnecting, thinking that would show something, but no change. Its only when doing a full reboot on the routerboard that any immediate change happens. Disabling and re-enabling the RB911G wlan interface does not reset anything as well.

- 6.33rc24 with wireless-cm2.
- Both ends using dual chain omni antennas

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lelmus
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Joined: Wed Oct 17, 2012 5:50 am

Re: RB922UAGS-5HPacD Dual Band AP - Poor Performance

Mon Oct 19, 2015 6:15 pm

I have the same setup RB922UAGS-5HPacD with R11e-2HPnD and I too have noticed decreased performance with wifi internal 5GHz, but wired computers to the CCR are flying. A reboot of the RB922UAGS-5HPacD corrects all slowdowns for awhile. Using 6.33rc24.
 
scampbell
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Location: Wellington, NZ
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Re: RB922UAGS-5HPacD Dual Band AP - Poor Performance

Wed Oct 21, 2015 11:21 pm

Neither radio card has a wireless protocol correctly set. Set both to wireless-protocol=802.11 and see if that helps.

R name="2gn" mtu=1500 mac-address=4C:5E:0C:11:0E:FC arp=enabled
interface-type=Atheros AR9300 mode=ap-bridge ssid="radio" frequency=2447
band=2ghz-onlyn channel-width=20/40mhz-eC scan-list=default
wireless-protocol=unspecified vlan-mode=no-tag vlan-id=1
wds-mode=disabled wds-default-bridge=none wds-ignore-ssid=no
bridge-mode=enabled default-authentication=yes default-forwarding=yes
default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=yes
security-profile=radio compression=yes

1 R name="5gac" mtu=1500 mac-address=4C:5E:0C:60:F2:1E arp=enabled
interface-type=Atheros AR9888 mode=ap-bridge ssid="radio" frequency=5500
band=5ghz-a/n/ac channel-width=20/40/80mhz-Ceee scan-list=5500
wireless-protocol=any vlan-mode=no-tag vlan-id=1 wds-mode=disabled
wds-default-bridge=none wds-ignore-ssid=no bridge-mode=enabled
default-authentication=yes default-forwarding=yes default-ap-tx-limit=0
default-client-tx-limit=0 hide-ssid=yes security-profile=radio
compression=yes

Also check if your frequency of 5500 is matched by your CPE on the 5GHz link. 5180 Ceee may be a better starting point if it's clear. Also setting the scan-list to one frequency (5500) on an AP is not helpful, better to leave at default or specify a range.
MTCNA, MTCWE, MTCRE, MTCTCE, MTCSE, MTCINE, Trainer
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