and welcome to the forum.
To help you get your NG Firewall configured properly, it would be great if you could go a little more into detail.
Did you follow the instructions mentioned here?
"Reverse Routing Interface Mismatch" usually indicates wrong routing on your NG Firewall.
To troubleshoot your situation, the following information would be helpful. Go to FIREWALL > History and search for the connection where you saw the Info message. Please verify the following connection details:
Source, Destination, Dst NAT, Interface, Output-IF
A working Dst NAT connection to an internal host within the DMZ look like this:
Source: 220.127.116.11 (Public IP address on the Internet)
Destination: 18.104.22.168 (WAN IP address of the NG)
Dst NAT: 172.16.0.100 (host in the DMZ)
Interface: dhcp (network interface the connection is received, typically the WAN interface of the NG)
Output-IF: port3 (network interface hosting the DMZ network)