Can I set the ewon to allow a Computer to print to a network printer on the WAN side of the ewon?
If you set NAT on WAN (NATitf=2) the computer will be able to reach the WAN. Make sure the computer’s default gateway is set to the LAN IP address of the Ewon, and reboot the Ewon.
Is this one way traffic? How does it affect the security?
Yes, this is one way traffic.
The Ewon will drop all incoming traffic if the default setting for WANitfProt is retained in comcfg.txt (Setup > System > Storage > Edit COM cfg). Please note: The default setting is 2 - Allow All until you connect to the VPN, then it is changed to 1 - Discard all except VPN and initiated traffic.
Even if it’s set to 2 - Allow all, no traffic will be forwarded to the LAN devices. In order to receive incoming traffic from the WAN to the LAN devices, you have to set up a proxy (port forwarding) or NAT 1:1.