Question about Acer Hotspot Connect M5

I have mine configured as bridge mode with the DMZ forwarding to an IP (where I have a Ubiquity Edge Router)... and that router does NAT...
The DMZ option tells you this:
"Note: If external users can't access certain network services provided by the Local Area Network (LAN), use the DMZ function to set the client that provides the required network services as the DMZ host. External users will then have access to all services. Note that clients in the DMZ will be exposed to WAN traffic. "
Basically, is a bridge.

A switch works. I don't know if a router works in bridge mode.

No there is no bridge mode