Tearing my hair out with this one! Any help gratefully received.

Draytek 2925 with firmware 3.8.2. Regular as clockwork the 5GHz Wifi (two SSIDs) crashes exactly every 10 minutes. The 2.4 GHz WiFi band and other router functions are unaffected and contribute to run normally. There is nothing in the syslog that gives any clue to the nature of the problem. The 5GHz band just stops broadcasting (confirmed by running a WiFI scanner on a laptop PC). After 70-75 seconds the WiFi comes back online, devices reconnect and I see WPA handshakes in the syslog. Then after nearly nine minutes uptime the WiFi crashes again and the 10 minute cycle starts over.

The 2.4GHz band is extremely congested at my location with very poor throughout and so 5GHz, which for now is completely clear, is a necessity. When it is running the 802.11ac WiFi reliably manages data rates around 70Mbps.

I have two iPhone 6 and and iPad Air 2 devices all with iOS 9.2 connected to the 5GHz band. DHCP refresh is set to the standard 86400 seconds.

Vax

Try turning off each of your devices one by one and see which one is upsetting the vigor.

Thank you, good tip. I tried one device at a time with the other devices switched off, and then no devices.

1. iPhone 6 (model MG4E2B/A) running iOS 9.2 (13C75)
2. iPhone 6 (model MG4F2B/A) running iOS 9.2 (13C75)
3. iPad Air 2 (model MH312B/A) running iOS 9.2 (13C75)
4. Lenovo X1 Carbon 2nd Gen PC (model 20A70066UK) running Windows 7 SP1 Build 7601. Intel Wireless-AC 7260 card with driver version 18.20.0.9

The 5GHz WiFi continued to crash at regular intervals regardless of which of my devices was connected or when in the crash cycle they connected. For the final test, with no devices connected to the 5GHz WiFi, I had all the Apple devices off and the Windows laptop on, but not connected. InSSIDer software was running on the laptop to monitor whether the 5GHz WiFi was up or down. Even with no devices connected the 5GHz WiFi continued to crash regularly.

During the above testing I've established that the WiFi doesn't in fact crash on every 10 minute cycle, but when it does crash it is always on a multiple of 10 minutes, and it crashes the majority of the time. The cycle is definitely 10 minutes rather than 20, 30 etc, but a crash is not guaranteed every cycle. I hope that makes sense! The 5GHz WiFi LED remains lit throughout.

Next I tried reflashing with firmware 3.8.2 (rst file) and then restoring config from a backup file. No change in behaviour, The WiFi crashed again after 10 minutes.

Any further suggestions gratefully received.

Vax

I'm not sure what you define a 'crash' as. Of course, there may be some other device
nearby of yours or a neighbour's. I'm not sure what else to check but you have mnore
useful info now at least.

I'm defining a crash as the loss of all 5GHz WiFi services, i.e.:

1. All 5GHz connected stations losing their link simultaneously.
2. All configured 5GHz SSIDs stop broadcasting.
3. No 5GHz connections being accepted for 70-75 seconds.

However the Draytek 2925 does not reboot and all other functions, including 2.4GHz WiFi continue running normally.

I don't have any other WiFi devices in ranges, as you say others may have, but they are not connected to my router.

Vax

Best ask support, but there may be some debug info in telnet commands or syslog.
It might just be faulty of course.

You're using a UK product/original PSU etc?

I wonder if it relates to DFS (it's their January Sale ! - No, not THAT DFS - ed).
See if you can disable the extended 5Ghz channels/DFS. Maybe it's doing a DFS scan every 10 seconds
and you've got an air force base next door.