Can't access from local network using the public IP, only from public network

Hi, I have the HA on a RPI on my private network. I can access to it using the HA’s local IP from my local network. I can also access to it using the public IP from outside of my local network. (The NAT is opened on my router) The problem comes up only if I want to reach the HA from local network, using my public IP. It simply doesn’t connect. First I thought it is some kind of network problem, but I have several other NAT port forwarding which doesn’t have this behavour.

My initial thought reading this was … Consumer grade routers often have this issue.

But, I see you have similar setup for other NATting. So, something is different somewhere. It might be better to search for your router brand/model and this issue.

Right, but what about ports?
What is the external port you are using to access HA?
What is the internal port set to?
Is there any sort of reverse proxy involved in the setup?

Thank you for help.
I use the default port: 8123. in both way.
“add action=dst-nat chain=dstnat dst-address-list=WAN dst-port=8123 protocol=tcp to-addresses= to-ports=8123”
The strange thing that I use this kind of rule for a Synology NAS without any problem. (On the port 5000 and other local IP of course)