I have an "ax4200 rax42" and I fought it for days trying to get the built in VPN Service working. Come to find out DMZ host and VPN service do not play nice together.
I would guess that VPN and DMZ should not be normally configured together. DMZ is mainly devices that need full exposure to the Internet resources with out any router management. Should be used carefully and only as needed. I don't believe VPN is supposed to be configured with any DMZ. Shouldn't be needed.
