ASUS System Log Warning – kernel: nf_conntrack: expectation table full message
OK, so I upgraded my RT-AC86U to ASUSWRT-Merlin latest firmware RT-AC86U_384.14_0
I noticed, probable there from previous versions, the following System Log messages.
- Dec 16 13:16:17 kernel: nf_conntrack: expectation table full
- Dec 16 13:16:30 kernel: nf_conntrack: expectation table full
The “kernel: nf_conntrack: expectation table full” log message is causing many log messages to be created and after a reboot of the router, browsing does appear to slow after 15 minutes or so.
So after some research I found the following post on the Billion Forum which indicated the log message could be related to the Firewall.
As it happened, I had recently disabled IPv6 on my ASUS router, but had not disabled the IPv6 Firewall.
IPV6 Firewall is now disabled and no more – kernel: nf_conntrack: expectation table full log messages
This is why I both love and hate ASUSWRT and ASUSWRT-Merlin, the annoyance of the problems followed by the relief of the fix/remedy 
P.S. “I am getting to old for this kind of crxp” ;-)