This is an RFC1918 address and is not publicly routable. Is your OpenWrt router directly connected to your internet connection, or is there another NAT device upstream (such as a modem+router combo unit or an ISP supplied router, etc.)?
Yes it is, it''s connected to a power line in my study which in turn connects to powerline in our living room where our ISP has placed the lan port to connect routers/modems
Port forwarding worked before on Archer C6 without any issues
My network is like this
I have plugged the Raspberry directly to the lan port at home, by passing both powerline devices, and the IP is still the same 10.112.101.23/25 even though my public IP starts with 185...... when I check it via curl ifconfig.me command
If you don't have any control on the ISP lan port, then you cannot do much. Most likely you are behind CGNAT and you can only discuss it with your ISP, if they can offer you a public IP.