protocol 00 is buggy (knockd+advanced monitoring off)

[mn66u]

I have an annoying problem and I am a total newbie on routers/Linux so I would need some advice on troubleshooting.

edit: Firmware Version:3.0.0.4.266.23

I have installed "knockd" from Entware and it is working just fine after me doing some googling on how to set it up.

However, it only works without errors if I have "Enable advanced (per IP) monitoring = Yes" under Tools -> Other settings.
I discovered this by chance since I read in this forum that HW-acceleration is disabled when advanced logging was set to YES so I thought I should turn it off.

With advanced monitoring enabled I get this in my syslog after a reboot:

2013-02-13 11:19:47	Daemon.Error	192.168.1.1	Feb 13 11:19:47 nmbd[702]:   Samba server RT-N66U is now a domain master browser for workgroup WORKGROUP on subnet xx.xx.xx.xx
2013-02-13 11:19:57	User.Notice	192.168.1.1	Feb 13 11:19:57 knockd: starting up, listening on eth0

no strange errors.

With advanced monitoring off I get this in my syslog after a reboot:

2013-02-13 11:12:49	Daemon.Error	192.168.1.1	Feb 13 11:12:49 nmbd[712]:   Samba server RT-N66U is now a domain master browser for workgroup WORKGROUP on subnet xx.xx.xx.xx
2013-02-13 11:12:57	User.Notice	192.168.1.1	Feb 13 11:12:57 knockd: starting up, listening on eth0
2013-02-13 11:12:57	User.Critical	192.168.1.1	Feb 13 11:12:57 kernel: protocol 0000 is buggy, dev eth0
...
2013-02-13 11:13:02	User.Warning	192.168.1.1	Feb 13 11:13:02 kernel: printk: 218 messages suppressed.
...

I start knockd via scripts/services-start but also put it in wan-start since I noticed it will die during some config operations when WAN interface is stopped, don't know if this is the correct way or not.. Removing it from wan-start has no effect on my problems anyways.

I start knockd by:
knockd -d -c /opt/etc/knockd.conf -i "$( nvram get wan0_ifname )"

I have VPN running but with no broadcast since I read that could cause similiar log entries.
Any suggestions?