Unauthorized 401 on IIS 7.5

I developed a WebService using WCF Data Services. Debugging it on my localhost using VS2017 (IIS 10) it works fine. Once deployed on the server,GET and POST work fine, PUT/PATCH/DELETE give a 401 error. IIS Logs say 401.3

I tried to switch from Anonymous Authentication to Windows Authentication, did not help.

I'm quite sure the problem relies in the IIS settings, but I'm not able to fix it.

Any hints?