RT-AX86U Pro - no auto-reconnect after WAN connection restore?

[Rici]

Hi,

Sometimes Xfinity loses connection for a short period of time, but after the WAN connection comes back (as indicated by the LEDs on the cable modem), my RT-AX86U Pro running Merlin 3004.388.5 does not automatically reconnect. While the WAN LED on the RT-AX86U Pro remains white, my WiFi clients connected to my RT-AX86U Pro report that there is no Internet connection.
Only after I manually reboot the RT-AX86U Pro the Internet connection comes back.

When looking at the system log, I can see entries such as

Jan  1 21:37:03 WAN(0)_Connection: WAN was restored.
Jan  1 21:37:03 rc_service: wanduck 1546:notify_rc start_dnsmasq
Jan  1 21:37:03 custom_script: Running /jffs/scripts/service-event (args: start dnsmasq)
Jan  1 21:37:03 dnsmasq[10705]: exiting on receipt of SIGTERM
Jan  1 21:37:03 custom_config: Appending content of /jffs/configs/dnsmasq.conf.add.
Jan  1 21:37:03 dnsmasq[27490]: started, version 2.89 cachesize 1500
Jan  1 21:37:03 dnsmasq[27490]: compile time options: IPv6 GNU-getopt no-RTC no-DBus no-UBus no-i18n no-IDN DHCP DHCPv6 no-Lua TFTP no-conntrack ipset no-nftset no-auth cryptohash DNSSEC no-ID loop-detect no-inotify no-dumpfile
Jan  1 21:37:03 dnsmasq[27490]: warning: interface br2 does not currently exist
Jan  1 21:37:03 dnsmasq[27490]: warning: interface br1 does not currently exist
Jan  1 21:37:03 dnsmasq[27490]: warning: interface pptp* does not currently exist
Jan  1 21:37:03 dnsmasq[27490]: asynchronous logging enabled, queue limit is 5 messages

The weird thing: Those messages, starting with WAN(0)_Connection: WAN was restored, repeat every 13 seconds or so.

With my previous Asus routers running Merlin I never had such issues.

What is wrong here, and how to fix it?

 

[bbunge]

There are lots of complaint on the internet about Asus routers loosing connection on Comcast. Some have success setting DHCP Query Frequently to continuous. Others have to have Comcast troubleshoot the connection.

 

[Rici]

Thank you. I now have set the DHCP Query Frequently to continuous.

With my previous RT-AX86U on the same modem and Xfinity account I never had this issue.

 

[Rici]

When further looking at my syslog the DHCP messages received from Xfinity don't hint to something broken on the DHCP side.

Instead, there are several dnsmasq entries which also look ok to me. The only thing is that those messages repeat every 13 seconds or so, always starting with that WAN(0)_Connection: WAN was restored message.

Are you sure that the Asus router is loosing the WAN connection d/t not liking Xfinity's DHCP stuff?

Or is this an issue caused by dnsmasq - as it constantly restarts?