Problem solved, I'm providing the procedure for anyone who might need it:

I want to point out that I'm not a PXE expert; some options may be superfluous. If there's anything to modify, feel free to do so below this post. This was done on a test environment, so some elements will need to be adapted to your setup.
On your DHCP server:
- Define the user classes
- Add
- Name = iPXE
- Description = iPXE Clients
- In your scope, from which PXE clients will retrieve their IP addresses
- Policies
- New policy
- Name = PXE (you can enter anything you want)
- Add
- Criteria = User class
- Operator = Is equal to
- Value = Select the user class name created previously
- Click Next until you can choose options
- Option #067 = http://
IP_SRV_WAPT/api/v3/baseipxe?uefi=false
- Add the following options to "Scope Options":
- 060 = support
- 066 = IP_SRV_WAPT
- 067 = undionly.kxpe
- In the end, you must have at least the following options:
- 060 = support
- 066 = IP_SRV_WAPT
- 067 = undionly.kxpe
- 067 = http://
IP_SRV_WAPT/api....
On your WAPT server
- As the TFTP server, I chose TFTPD by Ph.Jounin (you are free to choose another)
- In Current Directory: path to the WAPT pxe folder
- example: C:\wapt\waptserver\repository\wads\pxe
- In server interfaces: specify the interface to which Connect your WAPT server
- Finally, by clicking the settings button, check:
- PXE Compatibility
- Translate Unix file names
- Bind TFTP to this address =
IP_SRV_WAPT
- Allow "\" As virtual root.
Once everything is configured normally, if you start your PXE client, it should retrieve an IP address and display the menu allowing you to register the machine in the WAPT console.