ZyXEL Communications NXC5200 User Manual page 224

Chapter 14 NAT
replied directly to the LAN user without the traffic going through NAT, the source
would not match the original destination address which would cause the LAN
user's computer to shut down the session.
Figure 94 LAN to LAN Return Traffic
NAT
Source 192.168.1.21
Source 1.1.1.1
SMTP
SMTP
LAN
192.168.1.21 192.168.1.89
224
NXC5200 User's Guide