Since DSM 6, there is no longer /usr/syno/etc.defaults/rc.d/S01iptables.sh as mentioned in 2013 and 2014. The later thread mentioned the message, insmod: ERROR: could not insert module /lib/modules/nf_nat.ko: Unknown symbol in module, but till 2017, no one solve this problem.
Our company had set up 802.1X authentication for LAN. And the clerk said to link the LAN, all computers running Windows must join its domain to login with enterprise E-mail account. My PC was running continously before the change made, thus the LAN port keeps open.
However, after moving to another building, the new LAN port just shut me out, dhcpcd enp2s0 always return with “time out”.
I sent a ticket and the clerk told me, all LAN ports require 802.1X authentication now. If running Linux, I must setup a GUI to start the link.