Solved Router DHCP and DNS not responding to changes

[dave14305]

Have a look to make sure the AC68U is still in AP mode, and not running dnsmasq also.

 

[PTS]

No worries, I appreciate you taking me through this.

ps w | grep [d]nsmasq

 2406 nobody    2776 S    dnsmasq --log-async
 2408 Me           2644 S    dnsmasq --log-async

ifconfig br0

br0     Link encap:Ethernet  HWaddr 7C:10:C9:E1:FE:A0
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING ALLMULTI MULTICAST  MTU:1500  Metric:1
          RX packets:1394724271 errors:0 dropped:1502417 overruns:0 frame:0
          TX packets:2193259768 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1108087297488 (1.0 TiB)  TX bytes:2698158282352 (2.4 TiB)

 

[PTS]

Have a look to make sure the AC68U is still in AP mode, and not running dnsmasq also.

GUI shows it in AP mode, running `netstat -nlp | grep ":67 "` doesn't return anything

 

[dave14305]

Ah yes, there it is...
View attachment 56744

Do you still have the Wireshark file? Is the source MAC for this specific transaction the same as what is on br0?

 

[PTS]

Do you still have the Wireshark file? Is the source MAC for this specific transaction the same as what is on br0?

If you mean `HWaddr 7C:10:C9:E1:FE:A0` and the source for the ACK, then yes they're the same (it's the AX56U).

 

[dave14305]

Almost all wireless devices connect to R2.

Can you reboot the AC68U AP to force all the clients to renew their leases?

 

[PTS]

Can you reboot the AC68U AP to force all the clients to renew their leases?

Pretty sure I'd already done that but have just done it again. Phone and laptop haven't had a DHCP reservation on the 56U for a while now, but they're still being given the same IPs. They've still got 101 and 200 as their DNS servers too.

The client list does however show they're being handed out as DHCP rather than a manual assignment in the DHCP server:

 

[dave14305]

Can you add log-dhcp to /jffs/configs/dnsmasq.conf.add? Then run service restart_dnsmasq

This assumes you have custom JFFS scripts/config enabled on the Admin page. It will generate extra logs for the DHCP server.

Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  1 option: 53 message-type  5
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option: 54 server-identifier  192.168.1.1
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option: 51 lease-time  1d
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option: 58 T1  12h
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option: 59 T2  21h
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option:  1 netmask  255.255.255.0
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option: 28 broadcast  192.168.1.255
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option:  6 dns-server  192.168.1.1
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  1 option:252   0a
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  9 option: 15 domain-name  home.arpa
Feb 24 22:17:31 dnsmasq-dhcp[16837]: 1732646482 sent size:  4 option:  3 router  192.168.1.1

 

[dave14305]

I had to update the filename above. Otherwise, your dnsmasq would break… sorry.

 

[PTS]

Can you add log-dhcp to /jffs/configs/dnsmasq.conf? Then run service restart_dnsmasq

I didn't actually have that enabled so it's just been enabled. Navigating to /jffs/configs shows an empty directory. Should I add /jffs/configs/dnsmasq.conf to the directory?

 

[dave14305]

I didn't actually have that enabled so it's just been enabled. Navigating to /jffs/configs shows an empty directory. Should I add /jffs/configs/dnsmasq.conf to the directory?

You can run these commands:

echo "log-dhcp" >/jffs/configs/dnsmasq.conf.add
service restart_dnsmasq

 

[PTS]

I had to update the filename above. Otherwise, your dnsmasq would break… sorry.

just saw this. I created the /jffs/configs/dnsmasq.conf.add and added the log-dhcp line:

I then rebooted the router and changed the log levels, but not seeing any DHCP logs:

The mac 94:3A:91:E8:9A:73 is an Amazon Echo, I can't tell what the one beginning 1E is for. I'm also a bit confused to see skip the event lines. Is this relevant? The Password auth succeeded for... is for my Home Assistant integration and SSH into the router from the laptop.

 

[dave14305]

Make sure the /jffs/configs/dnsmasq.conf (bad) file isn’t there.

No need to change the routers log levels. You should be seeing dnsmasq logs if it’s running.

 

[PTS]

Make sure the /jffs/configs/dnsmasq.conf (bad) file isn’t there.

There was no change to the log output in the GUI since my last post here, which is weird to say the least.

But that 'skip event: reboot' got me thinking, and although there had been numerous reboots and power off at the switch, it was still showing 34 days of uptime. So I did a full power cycle on the AX56U. I don't know why I didn't try this before. But now the IP of my laptop has changed to 1.233, and the response to an nslookup is 1.105, which is what I was going for.

Very strange that nothing was updating properly when it should, and sorry to waste your time Dave and Colin. Really appreciate the help you gave, and I've learned some things from you.

 

[dave14305]

But that 'skip event: reboot' got me thinking

The restart of the firewall was not completing in time, so the logger restart and even a reboot attempt timed out. Odd for sure, especially if you have no other custom scripts.

 

[PTS]

The restart of the firewall was not completing in time, so the logger restart and even a reboot attempt timed out. Odd for sure, especially if you have no other custom scripts.

Confirmed, no scripts.

I'm wondering if something had gotten stuck in a loop somewhere and I hadn't noticed resources getting over-used, but they seem fine now:

Again thanks for all your help.