Strange log messages spamming log

I got this in my log
Jan 22 23:37:05 kernel: protocol 0000 is buggy, dev eth0
Jan 22 23:37:05 kernel: protocol 0000 is buggy, dev eth0
Jan 22 23:37:05 kernel: protocol 0000 is buggy, dev eth0
Jan 22 23:37:16 kernel: protocol 0000 is buggy, dev eth0
Jan 22 23:37:16 kernel: protocol 0000 is buggy, dev eth0
Jan 22 23:37:16 kernel: protocol 0000 is buggy, dev eth0
Jan 22 23:37:28 kernel: printk: 29 messages suppressed.
Jan 22 23:37:28 kernel: protocol 0000 is buggy, dev eth0
Jan 22 23:37:28 kernel: protocol 0000 is buggy, dev eth0

I read before in this forum that u had to turn off VPN broadcast. The problem is that I can't find that feature at all.

Router ASUS AC66U
Firmware: 3.0.0.4.266.23

Best regards Dive