RV50 not send SMS from WAN

Using the Airlink RV50 I’m trying to send an IP packet to send text messages. I was able to do this with no problems when I was connected directly to it and using the Ethernet port in LAN mode. I had to place it in WAN mode, however, so I could specify the gateway and get the server to see it. Once I put in WAN mode it would no longer accept the IP packet. Looking at my firewall I can actually see that it receives the packet and then bounces it right back out as if it were trying to forward it to the correct IP!

Is there a correct way to put the device’s Ethernet port in WAN mode and have it still accept IP packets to send an SMS?