NAT from the same external Network not work

[jochen35]

Hello,
We have the OPNSense behind a router of the ISP with a 28er public network. Behind the OPNSense we have a WebServer, which can be reached from the Internet by port forwarding (on TCP80, 443). This also works without problems. If you now use an IP from the 28er network, the port forwarding does not seem to work, because then the WebGUI of the OPNsense is loaded.

Where could the problem lie here.

greeting
Jochen