Re: Anyone else seen this. [Draytek rebooting]

On 04/07/2026 00:33, Theo wrote:
> In uk.d-i-y jkn <[email protected]> wrote:
>> On 03/07/2026 22:16, The Natural Philosopher wrote:
>>> On 03/07/2026 16:45, jkn wrote:
>>>> On 03/07/2026 16:21, The Natural Philosopher wrote:
>>>>> Recently my router (Draytek 2726) has been spontaneously rebooting.
>>>>>
>>>>> Examination of the logs show a kernel panic caused by 'attempt to
>>>>> execute an illegal instruction'.
>>>>>
>>>>> My assumption, possibly erroneous, is that the actual firmware code
>>>>> is corrupted
>>>>> The router is rated only to +45°C but that is the recommended limit
>>>>> for flash memory, and the room temperature has been up towards 40°C.
>>>>> which doesn't leave a great deal of margin for router internal heat
>>>>> production.
>>>>> My query is whether anyone else has seen issues with flash memory in
>>>>> the recent hear wave.
>>>>>
>>>>> Surely phones get hotter than this?
>>>>>
>>>>> Genuinely interested in other's experiences.
>>>>>
>>>>
>>>> I have a Draytek 2927 series - it is not new to me, but was previously
>>>> used in a commercial environment with no issues AFAIK.
>>>>
>>>> I have noticed a situation with mine where the connection both wired
>>>> and wireless) appears to drop momentarily, on occasion (couple of
>>>> times a week?)
>>>>
>>>> I recently looked at the log, and saw something similar to what you
>>>> describe - the router was in fact rebooting, and the log shows
>>>> something like:
>>>>
>>>>   > sys ver dbg
>>>>
>>>> Router Model: Vigor2927ax    Version: 4.5.2 English
>>>> Profile version: 4.0.0    Status: 1 (0x9de71d0f)
>>>> Router IP: 192.168.0.1    Netmask: 255.255.255.0
>>>> Firmware Build Date/Time: Feb 12 2026 17:45:01
>>>> Router Name: DrayTek
>>>> Revision: 6562_fd593bfca2 drayos2015
>>>> Router serial no: None
>>>>
>>>> ---------firmware exception debug info on
>>>> cpu0-----------------------------
>>>>
>>>> # etc.
>>>>
>>> Yes. that is significant. Its the next bit of the log before the
>>> registers dump that is significant
>>>
>>> Mine said (in shorthand) 'The CPU tried to execute an instruction that
>>> does not exist'
>>>
>>
>> Yes, my log has:
>>
>> ---------firmware exception debug info on cpu0-----------------------------
>>    EPC=60034b60, Cause=00800014, Status=1100fc03, BadAddr=00000000,
>> RetAddr=60034a58
>>    exception id=5(ADES: Address Error Store)
>>    exception occured in TASK Level
>>    task_id=161, SP=0x629390b8(3188 bytes free, 5664 used bytes)
>>    system tick =26381273
>>    CURRENT_VERSION : 4.5.2_RC5
>>    get from address : 60017000
>>    Dump CPU0 registers:
>> ...
>>
>>
>> but if you look eg. here:
>>
>> https://www.draytek.co.uk/support/guides/kb-troubleshoot-reboot
>>
>> they list a log like this - this seems a 'normal' feature of reboot
>> issues, without considering flash failure.
> 
> That looks like MIPS. The Cause register bits 2-6 gives you the type of
> exception. For yours:
> 
> Cause[6:2] = 5 which means 'Store to illegal address'
> 
> TNP's has:
> 
> Cause[6:2] = 10 which means 'Reserved instruction'
> 
> codes from:
> http://www.cs.iit.edu/~virgil/cs470/Labs/Lab7.pdf
> 
> They are different types of exception, even if the information is presented
> in the same way.
> 
> Theo

Agreed - but my point was, PSU issues could cause any or all of these...