DHCP not working - solved

[nlurker]

I had previously reported this frequently-recurring problem where DHCP would stop responding and I could not access the internet. Some others of you also reported this, so I wanted to share my solution. I replaced my USB stick several weeks ago, and this problem has not occurred at all since then. It never went this long before. So my conclusion is that using "any old" USB stick may not be the best advice. I am guessing that my "any old" USB stick was too slow, and dnsmasq was getting stuck in some sort of timing bug.

FLA_NL said: ↑
Did a dirty flash over 384.13 yesterday evening CET. This morning the DHCP was not working, the router indicated internet was down and the CPU usage was constantly high. Did a reboot and everything was working again. Now it's evening again and had the same issue. Reverted back to 384.13. Log did not indicate crashes while there was a high CPU usage. Router model is RT-AC86U.

This exact situation has happened to me many times over the last year with every merlin release during that time. The only pattern I have noticed is it has happened a few times at the exact moment I opened my laptop (on ethernet). But it has also happened at other random times, like in the middle of the night when I was doing nothing. Along with no DHCP and high CPU usage, the light on my USB stick was constantly flashing and felt hot.

 

[dave14305]

So another test could be to disable Diversion logging to avoid the USB writes for dnsmasq.

 

[nlurker]

So another test could be to disable Diversion logging to avoid the USB writes for dnsmasq.

Thanks! I had tried that before and it didn't seem to help. Replacing the USB stick has fixed it, so I am done troubleshooting. Just want to share that if you are having mysterious problems that others don't seem to have, it could be your old USB stick.

 

[datan]

just wanted to mention I had the exact same problem today.

- all wired and wireless clients disconnected
- rebooted couple of times
- could not get DHCP when connected by LAN
- manually assigned an IP address to connect to the admin page
- admin page was fine. everything looked normal except of course no clients could connect
- looked through the log files. seemed to have some mention of file locks unable to clear.
- replaced the USB stick with one that had already been formatted
- rebooted
- all is fine
- using both Diversion and Speedtest (scheduled) as well