I had the same issue and turned out it was the UPS. I got a cheap Eaton pure sinewave ups and it was ok. But I did have some random reboots afterwards and I think I set the hardware acceleration to auto and it was OK

It turns out to be 100% stable with wifi turned off. The unit is connected to a APC UPS (and has been since I got it), and all my other Drayteks (2820, 2800) have been fine.

Hardware acceleration is set at Auto.

Have an open ticket with DrayTek support, and after an initial round of syslogging, they think it is a caused by a USB device, which is rather curious as I don't have anything USB plugged into it!

running "sys ver dbg" from a telnet session did reveal the following:
File is /etc/btlog.txt

---

fimrware exception debug info

---

EPC=8039029c, Cause=00800008, Status=1100fc03, BadAddr=5e0c49e5, RetAddr=80390228
exception id=2(TLB Load)
exception occured in TASK level
task_id=161, SP=0x82200a10(3766 bytes free, 280 used bytes), [(void(*)(void))if_task_lan]
system tick = 37191
Firmware version : 3.8.0.1_RC3a


I am meant to wait for it reboot and then re-run the same command and report back....

and hey ho, it rebooted... offering up this handy error:

Revision: 49232 2925_380_wlan

---

firmware exception debug info

---

EPC=1100fc03, Cause=80a6ff68, Status=80c2276e, BadAddr=00000000, RetAddr=8002ef1c
exception id=26(Reserved)
exception occured in IdleTask Timeout
task_id=161, SP=0x821ed240(3766 bytes free, 280 used bytes),[]
system tick =1843447
CURRENT_VERSION : 3.8.0.1_RC3a
get from address : 80004000
Dump CPU registers:

---

$ 0: 00000000 fffffffe 00000010 00101000
$ 4: be100000 000000ff 00000008 00000078
$ 8: 80c227b2 00000000 00000008 00000033
$12: 80a6f1b0 83ca2980 80a6ff68 ffffffff
$16: 00000032 00000004 821ed34c 00000000
$20: 821ed32c d1b71759 10624dd3 51eb851f
$24: 00000018 806a98b0 00000000 00000000
$28: 00000000 821ed240 000186a0 8002ef1c
List a possible caller functions:

---

func( 0)=8002ef1c
func( 1)=806a98b0
func( 2)=80a6ff68
func( 3)=80a6f1b0
func( 4)=80c227b2
func( 5)=80c2276e
func( 6)=806c26b8
func( 7)=8002d670
func( 8)=806c26bc
func( 9)=80c227b3
func(10)=8002dd3c
func(11)=8002dd3c
func(12)=807b2332
func(13)=80323800
List backtrace functions:

---

func( 0)=1100fc03

Hmm. I have a 2925+ which does exactly the same. Can go for weeks without a reboot then 2 or 3 in one day. When I put a call in to Draytek they advised me to do a tftp reload of the firmware - which I haven't done yet and after seeing this thread I don't think I will. Doing a similar thing to you with the Web Console rather than telnet I got:

> sys ver dbg

Router Model: Vigor2925n+ Version: 3.8.0.1 English
Profile version: 3.0.0 Status: 1 (0x490f5e4c)
Router IP: 192.168.2.1 Netmask: 255.255.255.0
Firmware Build Date/Time: May 22 2015 18:06:07
Router Name:
Revision: 49232 2925_380_wlan

!!!Exception debug info is empty!!!
get from address : 80004000
Exception debug info is reset!!
>

Last time it reset was about 2 hours ago so I was hoping for more. Do you have to set something up for it to record exception debug? And do you know if there is any documentation on what console commands are available and what they do?

John

Is your router rack mounted? Mine is (on an official DrayTek shelf made from seemingly pig iron), and I'm pretty sure that it behaved perfectly before I racked it (using wifi extension cables).

Normally Draytek's first suggestion is load the reset firmware just to ensure you have a clean (and basic) config. I trimmed mine right back just DHCP auth for Sky Fibre and it still kept rebooting. Disabled wifi and it seemed to be as good as gold.

I might unrack it in a minute, just to prove to myself to myself that it is a combination of wifi and being in a cabinet.

Mine seems to auto fill the sys debug log, I imagine access is just the same (you can use putty as a telnet client, specify your admin details and then issue the same command)

Having removed it from the rack, it is still rebooting all the time. More useless DrayTek hardware it seems

When you next contact DrayTek about it, suggest they also look at my ticket for additional information [#DQ540217]