The images in this example are taken from a recorder model SF-XVR6116S.
In this image we see that the 16 analog cameras of the model under consideration can be replaced, and that it only has 2 extra IP cameras according to basic specifications.
Now, by activating this option locally, with the screen and the mouse...
We'll get the rest of the extra cameras. In this case, six more. That is 8 in total plus those that could be replaced, for a total of potential IP cameras of 16+8=24 units.
This option is only available on recorders that support this extension.
For the most recent firmwares (versions 4.X, due to be released in the middle of 2020), the same option will be found in the System menu: