We are running into a problem keeping stable wireless connections to the new cAP-ac units we purchased installed at our client’s location. I have just completed significant onsite troubleshooting of the problem, but haven’t found a solution yet. I am hoping someone on the forums can assist.
The Problem: We are experiencing disconnected RDP connections on handheld Motorola devices running Windows embedded, when connected wirelessly to the new Mikrotik cAP-ac units we installed in a large warehouse. Ping tests from my notebook through the cAP units to the gateway router result in very high jitter. Over several hundred pings, the ping results range from 1ms to over 1200ms. This is while my notebook is stationary and has an excellent signal to the nearest cAP.
Environment: 29 cAP-ac units have been installed in a very large 360,000 square foot warehouse. Each cAP is mounted about 4 foot below the correlated flat roof, spaced out throughout the warehouse. The roof is approximately 30 foot above the floor. In the warehouse there are 63 rows of skid racks. We have mounted cAP units on every other row.
Configuration: All cAP-ac units are centrally programmed using CapsMan, running on an RB3011 router. Only wlan1 is being used on each cAP and all cAP units broadcast the same SSID and use the same frequency. The 5ghz wlan interface is not being used at this time. DHCP client is enabled on the eth1 interface on each cAP. We initially had RouterOS version 6.43 running on both the CapsMan router and the cAP-ac units, but have upgraded to 6.44, without any improvement.
Troubleshooting steps we have tried:
Did a wifi analysis and turned off all devices using 2.4ghz channel 1.
Confirmed that all cAP units were provisioned to use channel 1, 20mhz channel width. WPA2 encryption enabled.
Changed the channel used by the cAPs to 11, but no improvement.
Upgraded firmware to 6.44 on the CapsMan router and on about 1/3 of the cAP units closest to where I was running tests - no change.
Configured one of the cAP units as a stand alone AP, not configured by CapsMan and turned off the other cAP units in that end of the warehouse. Connections through the stand alone cAP had the same ping jitter problem.
Logged into one of the cAP units and ran pings to the local gateway IP. The results were less than 1ms consistently. This would seem to rule out a problem on the ethernet network.
Setup one of the cAP units away from the metal roof so that it was located about 15 feet off the floor, and then turned off the other cAP units in that area of the warehouse. We did this to test whether proximity to the flat correlated metal roof had anything to do with the ping jitter. Connected our test notebook over wifi, to the test cAP, 15 foot off the ground and it did not make any difference. Over 100 pings to the local gateway IP, times varied from 1 to 600ms. Pings from my test notebook connected to the wifi on one of the cAP units to the IP of that cAP seems to show the same high jitter, as when pinging the gateway IP.
I have included a screen capture of the wifi analysis, showing the cAP units assigned to channel 1 and other equipment assigned channel 6 or 11. I have also attached a screen capture of the ping test results, showing extremely high ping jitter, when pinging the local gateway IP, through the cAP units. A third screen capture shows the registration of my test notebook to the cAP nearest me. I am not sure what I need to do to get this wifi network providing stable connections. Any suggestions would be appreciated!
WiFi (or any other radio equipment) doesn’t work well if there’s excessive interference. By configuring all cAPs to use same channel you created lots of interference. You better configure cAPs to use channels 1, 6 and 11 alternately … and do some planning so that the physical distance between cAPs operating on same channel is at maximum …
Picture shows large number of different devices … you should definitely migrate some (as many as possibke) to 5GHz (where you should stick to 20MHz channels to maximize number of interference-free channels).
Looks like some serious interference. Enable reselect interval on CAPsMAN to 15 minutes.
Reduce Tx power.
Install the cAPs in a zigzag format, not rows.
Possibly add more cAPs.
Local forwading.
Control channel- auto
Consider 10 MHz channels
Thank you for your suggestions.
We have installed the cAP units in a zigzag format throughout the warehouse, skipping every other row. I have assigned channel 1 through CapsMan, believing that the cAP units would share the airtime on channel 1, as long as there are no other strong interference sources on channel 1 or adjacent channels. Is this incorrect?
To test the theory of interference between the cAP units, I turned off all them off, except one, in about a third of the warehouse. Pings from my notebook through the one cAP unit still running, still produced high jitter. Does this seem to indicate an interference source other than the cAP units that does not show up on a standard 802.11 wifi scan?
Add access list rule on CAPsMAN to drop connections weaker that -65 or -70 depending on usage. This enables roaming of gadgets. Please implement above tweaks then give feedback.
After doing a bunch more testing, I found that the high ping times continue to be a problem even when all but one cAP unit is turned off and the single remaining cAP is configured as a stand alone AP, not configured by CapsMan. Further testing found that there are several 2.4ghz APs in the building with hidden SSIDs that we don’t have management access to. Because of this, I decided to try 5ghz instead of 2.4ghz for this project. Initially I configured just one cAP to use 5240mhz and ran ping tests though it. These test results were much better than what we were able to get using 2.4ghz, but still varied from single digit ping times to 30ms, to the local gateway IP.
Now I am trying to setup CapsMan to centrally assign the configurations to all 29 cAP-ac units spaced throughout the huge warehouse. I can get CapsMan to assign a single configuration to all cAPs and provsion wlan2 on each, but I would like to alternate between four different 5ghz frequencies, by assigning different configurations to the cAP units based on mac address. Sadly I don’t know how to do this properly, because when specify a specific radio mac address in a provisioning rule in CapsMan, it seems to ignore it and provision all of the cAPs, not just the one cAP with the matching mac address. Would someone tell me how to assign a given CapsMan configuration to a specific cAP by mac address, or point me to existing instructions that explain this process?
In Provisioning section of CAPsMAN there is a possibility to create items with different “Identity Regexp”.
You can draw virtual middle line, all caps located left from middle line will have suffix “L”, caps located right will have suffix “R”. (Do not forget to change Identity names of Caps)
in provision profile setup 2 items, one that will provision caps with “_L" and another one that will provision devices with "_R” for this profiles you can choose different frequencies.
And do not forget “Access List” rule mentioned before.
I believe the reason you want to have different configurations per cAP is so that you can assign frequencies. This may not be the best move.
Create the four channels or more on CAPsMAN, then set channel reselect interval to 15 minutes. This way, cAPs shall select the best channel amongst the preset.
Having the cAPs automatically assigned from several frequencies every 15 minutes sounds like an easier approach.
Where to a find the setting in CapsMan for the cAPs do a channel reselect every 15 minutes?
Thanks to those that have provided suggestions on this ongoing CapsMan & wireless config issue. I tried using CapsMan to automatically reselect the frequency on each of the 29 cAP-ac units in this 360,000 sq ft warehouse, but I found that too many of the APs were using the same 5ghz frequency. Because of this I have abandoned CapsMan for now and have gone with configuring each cAP-ac unit individually. Currently each AP has the same SSID, and encryption code, but the frequency is assigned in an alternating arrangement to keep the APs that use the same frequency physically separated - ie neighboring APs use different non-overlapping 20mhz assignments. With this configuration, ping times to the local gateway IP are better than before, but still not great. Here are the typical results we are seeing:
Ping statistics for 10.255.1.2:
Packets: Sent = 100, Received = 96, Lost = 4 (4% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 123ms, Average = 26ms
Here is the connection info from the test laptop:
Here is a graph if what the wifi analyzer sees:
We are also experiencing wireless devices constantly hopping from AP to AP. To combat this, I have added an access list rule that restricts access to clients with a -65 signal or better, like this:
/interface wireless access-list
add comment=“Restrict wifi connections to -65 or stronger” signal-range=-65..120
Sadly the rule above has not fixed the problem. I have also tried to manually decrease the TX power on the radios in the cAP-ac units, but when I do, I get an error that the feature is not supported. Any suggestions as to what I can do to stabilize the ping times and keep the wireless devices from hopping from AP to AP, even when located in one spot?
Reduce the number of cAP-ac units, so we don’t have to reuse a given frequency as much?
in this case should be added 2 rules like this. One rule allow access second denies.
/caps-man access-list
add action=accept signal-range=-65..120
add action=reject signal-range=-120..-66
I’m considering mikrotik for a large warehouse too.
The first thing I’m not so confortable with, is that I think omni antennas/APs are not best suited for this enviroments, but I didn’t find sector or panel APs that can cover only the ails.
anyway, did you use some software for planning?
I’m considering mikrotik for a large warehouse too.
The first thing I’m not so confortable with, is that I think omni antennas/APs are not best suited for this enviroments, but I didn’t find sector or panel APs that can cover only the ails.
anyway, did you use some software for planning?
Your APs can be reached well by the stations, thanks to the height and the metal roof. But the stations in the aisles between the racks cannot receive all other stations. If not already done, try “cts-to-self” or “rts-cts” hw-protection-mode.
Pings from my test notebook connected to the wifi on one of the cAP units to the IP of that cAP seems to show the same high jitter, as when pinging the gateway IP.
