Model :

Hardware Version :

Firmware Version :


Model: TL-ER6020
Version: 1.0.0
Connection type: PPPoE
System mode: NAT

Hi there,
I placed new CentOS7 server(, Fixed IP address) in Public mode DMZ.
But ping does not respond from WAN(e.g.

The default gateway on CentOS7 is, Primary DNS is
I think there is no obstacles between WAN and DMZ.

It can respond normally when I changed to Private mode DMZ, it works fine.
What can I fix this?