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UAP-XG strange behavior

[ Edited ]

Problem Statement:

UAP-XG connected to a Mikrotik RB450Gx4 on Comcast Gigabit tier Internet the throughput quickly drops from ~800 mbps after performing multiple sequential tests ( iOS App, macOS scanner app, internet speed test, and multi-GB file transfers for testing) leveling out between 500 mbps - 600 mbps. Apple clients (macOS | iOS) randomly get only 10 mbps - 20 mbps throughput that appears to be temporary because after repeated speed test attempts the throughput returns to 500 - 600 mbps. The throughput does not returns to ~800 mbps range, unless both the router and AP are rebooted.

 

Configuration:

Router: RB450Gx4 v6.4.27
Cable Modem: SurfBoard SB8200
Broadband Service: Comcast Gigabit Tier

Controller: UniFi SDN on GCP [Debian] v5.8.28

Access Point:

UniFi UAP-XG v3.9.42

Radios:

2G | 29dBm (1 | HT40)

5G | 28dBm (36 | VHT80)

5G | 28dBm (153 | VHT80)

Settings:

Enable Advanced Features is Disabled

Beacons > DTIM is 3

SSID is 1 | Default group | WPA2 Personal

 

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Re: UAP-XG strange behavior

Hello @cgrey001,

 

Please upgrade the UAP to 3.9.50

 

 

Regards,

Glenn R.

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Re: UAP-XG strange behavior

I tested throughput last night on 3.9.50.  It appears to have resolved the random throughput drop to ~20mbps.  Overall throughput no longer degrades to ~500mbps.  However, max throughput observed is ~730Mbps, which is slower than 3.9.42.  Consisent and stable, but lower performance on 3.9.50.

 

Notes:

  1. Compared to the UAP-AC-HD the client phy link speed on is wildly inconsistent.
  2. Testing is at 4ft and 12ft clear line of sight from the AP.
  3. Upgraded to 3.9.50 and experienced problems with HomeKit devices showing 'No Response'.
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Re: UAP-XG strange behavior

Hello @cgrey001,

 

Do you have Multicast and Broadcast filtering on?

Could you run a iperf3 test from a wireless device to a wired device?

 

 

Regards,

Glenn R.

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Re: UAP-XG strange behavior

Multicast and Broadcast filtering are not enabled.

 

I can't run iperf3 because almost all devices are wireless.  I do have a Synology DS718+ with WD Gold Enterprise Drives on the LAN.  I've been testing with file transfers of large mp4s to confirm.  The results are consistent with internet speedtest and the iOS app.

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Re: UAP-XG strange behavior

[ Edited ]

Hello @cgrey001,

 

How is your UAP connected? 1G or 10G?

800mbps is good plugged into the 1G port.

What types of speed are you expecting?

 

Also note that these are enterprise APs and they are programmed for high reliability and high client count, they are not build to run to the MAX on a speedtest.

 

 

 

Regards,

Glenn R.

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Re: UAP-XG strange behavior

I've tried connecting to both the 1G and 10G for the wired uplink port.  The UAP-XG is connected directly to the router switch port which is only 1G (successfully auto negotiating).

 

I would like to try to sustain 800mbps speeds.  This is something the UAP-AC-HD that was replaced was able to do.  Right now I'm about 100mbps shy of the goal.  Unfortunately, 3.9.50 has brought a host of other problems such as HomeKit devices showing No Response and Android disconnects.

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Re: UAP-XG strange behavior

Hello @cgrey001,

 

Go ahead and downgrade then... Are you connected to 2.4GHz or 5GHz?

Could you post your system config?

Settings > Maintenance > Support Info > Show System Config

 

 

Regards,
Glenn R.

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Re: UAP-XG strange behavior

I'm connecting the 5G network at VHT80 the PHY TX/RX rate is reported on the device as 1300.  However, it varies wildly and is not as stable as previously on the UAP-AC-HD.

 

I've attached the current config. Note that troubleshooting has included setting up separate 2G and 5G networks.

Screen Shot 2018-09-07 at 2.33.20 PM.png
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Re: UAP-XG strange behavior

Hello @cgrey001,

 

Could you post the results from the wireless theoughput from the UniFi app?

 

 

Regards,

Glenn R.

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Re: UAP-XG strange behavior

Sure. Once I'm back on site.

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Re: UAP-XG strange behavior

I realized that since my Controller is in GCP that the iOS App WiFi throughput test does not really mean much.

 

Anyway, the network seems to have stablized.  My guess is that guest have distributed across the radios since I haven't rebooted in a while.  Load average is balanced across all the radios now. The throughput is back to the ~800mbps range on 3.9.50.

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Re: UAP-XG strange behavior

Hello @cgrey001,

 

Thats awesome!

Wish you the best with your sites!

 

 

Regards,

Glenn R.

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Re: UAP-XG strange behavior

I thought the problem was resolved with 3.9.50. Unfortunately, it’s back. 

 

I believe it’s related to VHT80 Channel 149 setting. All devices on 5G are affected by this behavior regardless of the 5G radio. 

 

The PHY connect rate is strong (866, 1300, etc), but the Speedtest are very inconsistent less than 20mbps with ping times in 32ms range to very good 700-800mbps with 11ms pings.  This is across iOS, macOS, and Android.  It seems to cause major problems with streaming. 

 

1BCB0A9A-7C28-45CF-A792-52F34E031E46.png54968050-F3E9-4A43-8919-DA48122B98E4.png

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Re: UAP-XG strange behavior

RF Scan for reference

 

6B664A7B-DE9A-4B74-8DF7-45A05C695A29.png

 

@UBNT-Tony FYI another issue I’m having with 3.9.50. So far, the reboot on provision, Android intermittent connectivity, and inconsistent throughput. The last two are probably related. 

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Re: UAP-XG strange behavior

[ Edited ]

So I've had some time to think about the problem.  I'm completely confused how changing the channel from 149 to 153 makes a difference since I'm using VHT80.  I was under the impression that 149-161 is a single channel represented by either 149 or 155.  Most recommendations are to set the channel at 149 for VHT80.  My understanding is that the channel selection is really only used for the beacon in the case of VHT80. 

 

So how is selecting 149 causing the sporadic throughput (severe drops)?  Why does this impact a client on the other 5G radio on channel 36?

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