IP passthrough not workng constently RV50X

Hello,
I am having an issue with IP passthrough intermittently not working on a RV50X with ALEOS v4.14

We put the modem into production last week, it worked for a few days, then the DMZ device dropped out.
I rebooted the modem several times to no avail. I see nothing interesting in the logs. I then turned off the IP Passthrough, the DMZ host got an internal address and things are working. I need the DMZ device to get the public IP in some instances, so disabling passthrough it not an option. Has anyone figured out this intermittent passthrough issue? Yes, I have read the post " RV50 IP Passthrough to DMVPN Cisco Routers - DMVPN Tunnel flapping"

Steven,

We certainly haven’t found it for our situation, but we’ve had good luck with setting DMZ mode to automatic in those passthrough cases and it seems to work as other suggested, but that is obviously for our situation and may not be suitable for all situations.

Thanks for the response. I’ve got one other RV50X and 4 RV50s working successfully with IP passthrough.
I just looked at the RV50X that seems to be behaving and came up with these settings that seem to work:

Security->Port Forwading: DMZ Host enabled, Port forwarding enabled (despite not using it)
LAN-> DHCP/Addressing: IP Passthrough Ethernet, IP Passthrough Mode First Host Reset Host Interface enabled.
LAN->Ethernet: DHCP Mode Auto

We’ll see if these settings work consistently; it had been working with DHCP and port forwarding disabled, but then stopped working with no settings change.