[SOLUTION] WAN_Connection: ISP's DHCP did not function properly

[garycnew]

All:

Recently, my Asuswrt-Merlin syslog.log started complaining that "WAN_Connection: ISP's DHCP did not function properly" with WAN0 disconnecting and reconnecting every couple of minutes, which was very noticeable while web browsing.

Apr 19 16:02:49 router-wap01 WAN_Connection: ISP's DHCP did not function properly.
Apr 19 16:02:49 router-wap01 DualWAN: skip single wan wan_led_control - WANRED off
Apr 19 16:03:09 router-wap01 WAN_Connection: WAN was restored.
Apr 19 16:03:10 router-wap01 nat: apply nat rules (/tmp/nat_rules_eth0_eth0)
Apr 19 16:03:10 router-wap01 custom_script: Running /jffs/scripts/nat-start
--
Apr 19 16:04:46 router-wap01 WAN_Connection: ISP's DHCP did not function properly.
Apr 19 16:04:46 router-wap01 DualWAN: skip single wan wan_led_control - WANRED off
Apr 19 16:05:12 router-wap01 kernel: [tdts_shell_ioctl_stat:256] Recv ioctl req with op 2
Apr 19 16:05:58 router-wap01 WAN_Connection: WAN was restored.
Apr 19 16:05:58 router-wap01 nat: apply nat rules (/tmp/nat_rules_eth0_eth0)
--
Apr 19 16:06:55 router-wap01 WAN_Connection: ISP's DHCP did not function properly.
Apr 19 16:06:55 router-wap01 DualWAN: skip single wan wan_led_control - WANRED off
Apr 19 16:07:03 router-wap01 WAN_Connection: WAN was restored.
Apr 19 16:07:03 router-wap01 nat: apply nat rules (/tmp/nat_rules_eth0_eth0)
Apr 19 16:07:03 router-wap01 custom_script: Running /jffs/scripts/nat-start
--
Apr 19 16:08:15 router-wap01 WAN_Connection: ISP's DHCP did not function properly.
Apr 19 16:08:15 router-wap01 DualWAN: skip single wan wan_led_control - WANRED off
Apr 19 16:08:26 router-wap01 WAN_Connection: WAN was restored.
Apr 19 16:08:27 router-wap01 nat: apply nat rules (/tmp/nat_rules_eth0_eth0)
Apr 19 16:08:27 router-wap01 custom_script: Running /jffs/scripts/nat-start
--
Apr 19 16:10:18 router-wap01 WAN_Connection: ISP's DHCP did not function properly.
Apr 19 16:10:18 router-wap01 DualWAN: skip single wan wan_led_control - WANRED off
Apr 19 16:10:23 router-wap01 WAN_Connection: WAN was restored.
Apr 19 16:10:24 router-wap01 nat: apply nat rules (/tmp/nat_rules_eth0_eth0)
Apr 19 16:10:24 router-wap01 custom_script: Running /jffs/scripts/nat-start

I tried the usual "MAC Clone" and "DHCP query frequency (Normal Mode)" changes without success.

I thought it might be the ethernet cable to the WAN0 port going bad, so I swapped it without success.

Then, I started to think it might be the WAN0 port itself and was considering enabling Dual WAN to test on the ETH0 port.

However, knowing that my ISP assigns the same address for years at a time, I elected to configure the address, netmask, and gateway statically to bypass the DHCP process--which worked and proved that it wasn't WAN0 going bad.

Nothing on my Asuswrt-Merlin's router config had change for many months, so I contacted my ISP to confirm whether any changes had been made to their DHCP Server as I suspected there was a recent incompatibility with my router's DHCP Client requests and the ISP's DHCP Server responses.

The ISP Tech was kind enough to enable the GE2 on the Fiber Modem and place it on a different VLAN with a different DHCP Server to find there were no issues with my Asuswrt-Merlin router. We then placed the Asuswrt-Merlin router back on GE1 of the Fiber Modem and the Asuswrt-Merlin router started working on the original port, again.

At this point, I'm not sure what the issue was, but am glad the problem is resolved for now.

I don't believe in Gremlins, but issues like this almost make me a believer.

Hope these troubleshooting steps help others in the future.

Respectfully,


Gary

 

[Tech9]

the problem is resolved for now

This issue is coming and going, perhaps specific ISPs related, people reported different solutions from simple call to the ISP to router replacement. Seems like Asus routers have some intermittent issue with restoring WAN connection when ISP device loses connection momentarily or at the time of DHCP lease renewal. I have never seen this happening on my ISPs, but there are many threads around mentioning similar issues. Lately the situation seems to be better. Few years ago there were more complaints.

 

[garycnew]

This issue is coming and going, perhaps specific ISPs related, people reported different solutions from simple call to the ISP to router replacement. Seems like Asus routers have some intermittent issue with restoring WAN connection when ISP device loses connection momentarily or at the time of DHCP lease renewal. I have never seen this happening on my ISPs, but there are many threads around mentioning similar issues. Lately the situation seems to be better. Few years ago there were more complaints.

@Tech9

Yeah... I read through a number of the similar threads, which provided some points for troubleshooting.

It's difficult to tell if the Asuswrt or the ISP DHCP Server is the culprit. As I stated... Nothing (firmware or config) on the Asuswrt side changed.

I've changed the title of this thread to [SOLUTION] as it sounds like there could be many.

Thanks for your feedback.

Respectfully,


Gary