Hi Ricardo,

Go to the ‘Network > One-to-One NAT’ page.
Check the box next to ‘Enable One-to-One NAT’, and click on the ‘Apply’ button.
Click on the ‘Add…’ button.
Enter the address of your server in the 'Private Range Start:' box.
Enter the Public IP address in the 'Public Range Start' box.
Enter '1' in the 'Range Length' box.
Click on the 'OK' button.

Then you need to allow this traffic through the firewall rules.

Go to the ‘Firewall > Access Rules’ page.
Click on the ‘Add…’ button.
Select 'Allow'
Select the 'Service' that you are hosting on the server (for example 'Web (HTTP)' if the camera uses TCP port 80).
For the 'Source' select '*' and '*' for the 'Address Range Begin' box.
For the Destination select the interface where the server is located, and enter it's IP address in the 'Address Range Begin' and 'Address Range End' boxes.
Click on the 'OK' button.

That should then allow someone on the Internet to access the camera using the service you have specified in the rule.