RT-AC87U random rebooting with 380.65 (Asuswrt-Merlin)

[Shin K.]

Hi! I've had this issue (random rebooting) before with my RT-AC87U on official firmware. The router would simply reboot on its own very frequently, especially after the latest official firmware update. I'm certain the problem is not in the hardware as earlier firmware releases have worked relatively better. I finally decided to flash the latest 380.65 Asuswrt-Merlin release, hoping it's better than the official firmware.

After the Asuswrt-Merlin upgrade, I reset the router to the factory settings and configured everything from scratch. My RT-AC87U held up for much longer without a reboot on the Asuswrt-Merlin firmware, but now after 8 days the router rebooted on its own again. Here's the relevant part from the log: http://pastebin.com/wbpuen8A

What can/should I do? Any help is appreciated. Thank you!

EDIT: I'm sorry that I can't paste the log here. I keep getting an error I'm blocked from using the SNBforums for violating a security measure. The pastebin link is hopefully accessible.

 

[Dean Stacey]

It may be power related, you might try a small battery backup UPS. There are a couple for around $40 that would fit the bill.

 

[joegreat]

Do you use a USB drive with your router with AiCloud? Or any other advanced options like AiProtection?
In this case the router could run out of memory - a swap file could help here.

 

[Beherit]

As I'm running all sorts of services on my RT-AC87U, memory can get tight in many situations. This caused all sort of weird issues, forcing me to reboot every now and than to gain back internet access. The primary cause of this was that I have IPv6 enabled, which causes the router to use much more memory than having it disabled.

I solved this by enabling swapfile usage on a USB memory stick: https://mydevtutorials.wordpress.com/2014/01/10/how-to-activate-swap-on-asus-rt-ac68u-router/

A while later, I found @kvic 's NTP Daemon, which uses far less memory than the default NTPd: https://www.snbforums.com/threads/ntp-daemon-for-asuswrt-merlin.28041/

That one freed up enough memory to make swapfile usage redundant for me. Feel free to try either, or both workarounds.

(EDIT: corrected link)

 

[joegreat]

A while later, I found @kvic 's NTP Daemon, which uses far less memory than the default NTPd:

The correct link to the NTP Deamon thread is this one:
https://www.snbforums.com/threads/ntp-daemon-for-asuswrt-merlin.28041/

On the latest Merlin firmware (with updated Busybox) the ntpstats.sh script produces an error and need be changed as outline here - @kvic will upload a new version to avoid this error as soon as he finds the time to do so.

But still a swap file is needed to avoid issues with memory shortage - especially when you use multiple services (as I do - see below).

 

[john9527]

Asuswrt-Merlin firmware, but now after 8 days the router rebooted on its own again. Here's the relevant part from the log: http://pastebin.com/wbpuen8A

What can/should I do? Any help is appreciated. Thank you!

Do you have either gui or ssh access open to the WAN? During the reboot there is a kernel panic referencing 'nvram_get' which is unusual..

 

[raduzl74]

If I create a SWAP on a 8 GB drive shall I make 8 GB swap file? Or what size shall I do it?

 

[joegreat]

If I create a SWAP on a 8 GB drive shall I make 8 GB swap file? Or what size shall I do it?

Swap size should be around the same size as you have memory installed: Typically 256 MB - more is overkill and does not bring any value.

 

[raduzl74]

RT-AC87U has 256 MB of DDR3 RAM so I'll do a 256 MB swap file. Thanks!

 

[Bogey]

My RT-AC87U has 256 MB swap file, I'm using kvic's NTP deamon. Memory stats proof ok in the tools screen, swap has 0 used and Free memory is 171.18 MB. Temperatures show 2.4 GHz: 39°C - 5 GHz: 52°C - CPU: 63°C. Underneath the router are fans blowing air in.
Yet the router reboots even more frequently than ever before. It has been once a week, then once a day and now multiple reboots a day.
Any suggestions?

 

[kvic]

I made a note to remind myself but always forgot to respond. Thanks for the "honourable mentions" a few posts back. Somehow I didn't receive those alerts or else I would have reacted earlier. lol

Yet the router reboots even more frequently than ever before. It has been once a week, then once a day and now multiple reboots a day.
Any suggestions?

Maybe do a factory reset, and manually configure your router again. Hopefully your issue is gone by then (or the crash interval is extended long enough you won't bother).

If issue persist, do a daily snapshot by SSH into your router and "cat /proc/meminfo /proc/slabinfo >> /jffs/mem.txt". Once you collect a few days' data. Post here. Some of us may help to do analysis.

 

[Bogey]

Thanks kvic.
I followed your advice. Unfortunatly no change. Asus support suggested to install a particular firmware, which I did, and reconfigure manually too. If that didn't fix the rebooting, the router's failing. And indeed it didn't fix it. So I returned the router to the seller and they too concluded it's defective and made a refund.