WiFi + short DHCP lease = problem?

RouterOS Wireless Networking
1

Hi

I have been having really bad experience with my RB2011UiAS-2HnD-IN WiFi in the office. My apple laptop and my colleagues iPad kept disconnecting regularly. I have been struggling much with the logs on the router like

12:13:33 wireless,info A4:5E:60:xxx@wlan-practi-office: reassociating
12:13:33 wireless,info A4:5E:60:x@wlan-pxxracti-office: disconnected, ok
12:13:33 wireless,debug wlan-practi-office: A4:5E:60:xxx in local ACL, accept
12:13:33 wireless,info A4:5E:60:xxx@wlan-practi-office: connected
12:13:35 wireless,debug wlan-practi-office: A4:5E:60:xxx attempts to associate
12:13:35 wireless,info A4:5E:60:xxx@wlan-practi-office: reassociating
12:13:35 wireless,info A4:5E:60:xxx@wlan-practi-office: disconnected, ok
12:13:35 wireless,debug wlan-practi-office: A4:5E:60:xxx in local ACL, accept
12:13:35 wireless,info A4:5E:60:xxx@wlan-practi-office: connected

every 10 minutes or so. On the laptop it would look like missed pings - between 1 to 6 pings (1 hz rate)

On the MAC console I saw this for every reassociate

 Fri Nov  4 14:23:36.853 <kernel> Received Deauth from e6:8d:8c:xxx with Reason 1
Fri Nov  4 14:23:36.855 <kernel> Unexpected payload found for message 34, dataLen 2
Fri Nov  4 14:23:36.855 <kernel> payload Data 01 00 
Fri Nov  4 14:23:36.856 Driver Event: <airportd[71]> _bsd_80211_event_callback: APPLE80211_M_ROAM_START (en0)
Fri Nov  4 14:23:36.856 Info: <airportd[71]> Roaming started on interface en0
Fri Nov  4 14:23:36.856 Info: <airportd[71]> SUSPEND AWDL behavior for interface en0
Fri Nov  4 14:23:38.169 <kernel> en0: roam event, sending supplicant link down message.

I also ran some wireshark logs and was actually surprised to see lots of broadcast deauth from the mikrotik..
Screen Shot 2016-11-04 at 19.47.57.png
While my computer was reauthenticating automatically, half of the iPads would loose wifi and not attempt to associate after 10-15 mintues, without regards if the data connection was being used or not

So eventually I tried removing the 10 minutes DHCP lease timeout and putting it to 2 days.

And that was it! no more disconnects.

Is this a feature? or a bug? Or maybe I don’t get it right? There were definitely refreshes happening, I saw it in the leases logs.

2

A note from some knowledgeable people would be highly appreciated. Thanks

3

It is an iOS dhcp bug.

https://www.net.princeton.edu/apple-ios/ios41-allows-lease-to-expire-keeps-using-IP-address.html

To my knowledge the bug has never been fixed, but changes in versions since this article was authored has changed the behavior of the bug. A 8-12h lease is usually sufficient, depending on usage. I personally use 24h on my network.

4

But the logs and packet sniffing show that it’s the Mikrotik that sends deauth

5

erased

6

This is described in the first post.

This has nothing to do with the problem.

@ulysses Which RouterOS Version and wireless package do you use?
Please adjust DHCP lease time as suggested and post your results.