I have been asked to look into some wifi issues being experienced in a large house. The equipment in use is a Draytek 2860 router, 6 x Draytek 910C wifi access points and 2 x Draytek P2261 managed switches. The 910Cs are POE powered by the primary switch. The 910Cs are all set-up and managed using the AP management feature built into the router.

Every 2-3 weeks, the wifi suddenly fails, whereby some mobile devices cannot connect to the access point, others appear to connect but are unable to access the internet. Wired Ethernet access continues to work OK. The problem is resolved by rebooting the router and switches, and waiting a few minutes.

The last time it happened, the homeowner managed to connect to the Access Point management area in the router, and could see that 4 of the 910Cs were showing as offline (RED) and 2 were showing as OK (GREEN).

I visited the site yesterday for the first time, and verified that the network set-up seems sensible in terms of DHCP, IP address range and use of fixed IPs etc. During my visit all the devices worked well and there were no signs of any problems.
I did notice that all of the devices were using quite old versions of the firmware so I decided to upgrade all devices to the latest firmware as follows:-

Device Old firmware New firmware
2860 router 3.8.5.1 (10/11/17) 3.8.9.3
910c access points 1.2.3.1 (20/10/17) 1.2.7
P2261 switches 3.3.5 (6/3/17) 3.4.8

I am now waiting to see if the problem occurs again, in which case I will do some more fault finding.

I am looking for some advice on how I might best fault find this problem? What is the best method of capturing the cause of the fault, next time it happens?
Are there any known problems with the old firmware, which might now be resolved given that everything is now on the latest firmware?

Your advice will be much appreciated

Michael McDonald

Are you using AP management from the router ?

"The problem is resolved by rebooting the router and switches,"

I'd try the router firstly, then check, before the switches to eliminate the router from the cause.

admin wrote: Are you using AP management from the router ?

"The problem is resolved by rebooting the router and switches,"

I'd try the router firstly, then check, before the switches to eliminate the router from the cause.

Yes, I am using AP management in the router. Next time it occurs I will try your suggestion of restarting the router first. Thanks.

Ensure you're using latest firmware on all devices too.
If rebooting the router fixes it, after that, disable APM and see if that prevents it reoccuring.

I have had similar issues using AP Management on both 3900 and 2960 using the 910c, the problem would be that after 7 to 10 days the clients would fail to get a DHCP leased via the WiFi. The solution was to stop using AP Management and setup the 910c manually.

This occurred on five different locations and Draytek have confirmed that there is NO known issue.

Afternoon all,

After several months of smooth operation, my customer has experienced connection problems again. Unfortunately, I did not have the opportunity to reboot the router, as suggested in this forum, because my customer had already rebooted the whole IT rack before he notified me. I have not yet tried disabling APM, but intend to on the next opportunity.

I did check the log files on all of the 910c access points and on 2 of the 6 devices I found some suspicious entries repeated over and over again, like

Feb 28 15:38:38 kernel: Wireless 2.4G, Qidx(0), not enough space in MgmtRing, MgmtRingFullCount=1728!
Feb 28 15:38:38 kernel: Wireless 2.4G, Qidx(0), not enough space in MgmtRing, MgmtRingFullCount=1792!
Feb 28 15:38:38 kernel: Wireless 2.4G, Qidx(0), not enough space in MgmtRing, MgmtRingFullCount=1856!
Feb 28 15:38:38 kernel: Wireless 2.4G, Qidx(0), not enough space in MgmtRing, MgmtRingFullCount=1920!

I wonder if anyone knows what this message means, whether it could be linked to the wifi disconnections and how do I go about solving it?

Thanks again