Your OpenWrt router does not have a public IP on its wan interface.
I guess you have an ISP provided device acting as an upstream router for you.
If the ISP device has a public IP assigned, then it should have either DMZ or port forwarding configured as well. I would start from checking these settings.
Since your OpenWrt is configured as DHCP client you will probably need to configure a static mapping for it on the upstream router, or just allocate the address statically.
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