Problem with redirected traffic to internal server.

Hello,

I have redirected my public IP address to a web server in my internal network.
I use the internal IP address 192.168.88.251 port 80. And this works.
Now I have a problem because when I try to access the <external ip from my browser on port 80 this does not work>
The telnet to the port also does not work.
NAT rule is:
chain= dstnat protocoll = tcp dst-port=80 in-interface-ether1 action=dst-nat to-address=192.168.88.251 to-ports=80

I tried many ways from the forum pages, but somehow I can not access the page using my router IP.
This is needed as I use domain names for the web server and I can not access all applications hosted on the web server.

Any ideas what needs to be done so that I can access the internal web server by using the router external IP.
I assume some redirect/nat rule is needed, but somehow I do not know how to do this.
Thanks for any advice.