Router locking up?

[nug]

This is happening intermittently, but my AC68U router sometimes hangs up and doesn't respond to ping. Internet access stops working as well.
I'm not quite sure what's causing this as when I force reboot, the logs aren't saved. Is this (logs not being saved) normal behaviour when shutting the router down via the switch at the back? After restarting the router the logs end on April 7 with the next entries recording the router booting up.
/tmp/syslog.log records the latest info whilst /jffs/syslog.log ends on the 7th.

Thanks for your help

 

[mstombs]

Re the jffs logs, I have pointed this out before the jffs copying code doesn't look correct to me, but to fix it would mean more flash writes which I am not a fan of - see

https://github.com/RMerl/asuswrt-merlin/blob/master/release/src/router/rc/watchdog.c#L1925

Once /tmp/syslog.log has rotated to /tmp/syslog.log-1, and a new syslog.log created how often will it copy to flash?

jffs does write cache and only writes full erase-blocks to minimize flash wear so quite likely a crash or power-off loses data. Linux has a command "sync" intended to flush ram caches, and you would expect the equivalent to executed in a more orderly shutdown or commanded reboot.

So logfile pretty unlikely to be useful for crashes, you could run a syslog server on another machine and might get more messages (udp broadcast) from just before a crash - but monitoring a serial console connection might be the only way to see a kernel oops... but not a hardware crash!

 

[nug]

Thanks for your reply mstombs. I'm not quite sure how to go about trouble-shooting these router hangs as they occur infrequently. It's only happened twice so far but ideally it wouldn't happen at all.
I noticed that when the router hung up, I could still communicate with other computers on the network (e.g. ping) for a short period after internet access stopped working and the router stopped responding to ping. I don't know if that means anything though.

 

[Fuzzy_Dunlop]

My AC68U was doing the same after upgrading from 378.51 to 378.52_2. After this happened 3 times I downgraded to 378.51 and haven't had any more problems. I've been extremely busy so I didn't have time to troubleshoot or attempt to clear NVRAM and re-setup everything.

 

[nug]

I haven't yet upgraded to .52_2 and have only been using .51. I think the two times it has happened has been about a week apart so it's hard to determine the cause...