405 not allowed error when submitting form

Hello! I am trying to set a form to send client contact info however whenever I try to test it in the published site it gives me a 405 not allowed error. Why could that be happening?
Thanks in advance.

Here is my site Read-Only: LINK

Hi there, on which page/ form do you have this problem?

Thank you for answering, it’s on the home page, the form is called contacto. I believe it shows as Form Block 4.