Powershell Invoke-RestMethod over HTTPS

I'm trying to communicate with a service over powershell but I am failing miserably. I suspect it is the certificate and I have googled for the answer and found two options, none of which worked for me. I have also tried to combine the two unsuccessfully.

Option 1:

add-type @"
    using System.Net;
    using System.Security.Cryptography.X509Certificates;
    public class TrustAllCertsPolicy : ICertificatePolicy {
        public bool CheckValidationResult(
            ServicePoint srvPoint, X509Certificate certificate,
            WebRequest request, int certificateProblem) {
            return true;
        }
    }
"@
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy

$urlJSON = "https://internal.ad.local/path/api_jsonrpc.php"

#Create authentication JSON object using ConvertTo-JSON
$objAuth = (New-Object PSObject | Add-Member -PassThru NoteProperty jsonrpc '2.0' |
Add-Member -PassThru NoteProperty method 'user.authenticate' |
Add-Member -PassThru NoteProperty params @{user="user";password="password"} |
Add-Member -PassThru NoteProperty id '2') | ConvertTo-Json


Invoke-RestMethod -Uri $urlJSON -body $objAuth -method "Post"

Option 2:

[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}

$urlJSON = "https://internal.ad.local/path/api_jsonrpc.php"

#Create authentication JSON object using ConvertTo-JSON
$objAuth = (New-Object PSObject | Add-Member -PassThru NoteProperty jsonrpc '2.0' |
Add-Member -PassThru NoteProperty method 'user.authenticate' |
Add-Member -PassThru NoteProperty params @{user="user";password="password"} |
Add-Member -PassThru NoteProperty id '2') | ConvertTo-Json


Invoke-RestMethod -Uri $urlJSON -body $objAuth -method "Post"

Here's the error message:

Invoke-RestMethod : The underlying connection was closed: An unexpected error occurred on a send.
At C:\Users\user\AppData\Local\Temp\46eaa6f7-62a0-4c10-88d1-79212d652bc9.ps1:24 char:1
+ Invoke-RestMethod -Uri $urlJSON -body $objAuth -method "Post"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
    + FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

I might add:

• surfing directly to the service works with a web browser
• I tried opening up to HTTP as well, and that worked
• The certificate used by the service is self-signed but trusted by my machine via a root certficate (no warnings is issues in IE or Chrome)
• I have done network captures and made sure that a packets does indeed reach the server.

Any suggestions appreciated!

Kind regards, Patrik

Updated post as to suggestions made by Mr Tree below:

Name                       : lambda_method
DeclaringType              :
ReflectedType              :
Module                     : RefEmit_InMemoryManifestModule
MethodHandle               :
Attributes                 : PrivateScope, Public, Static
CallingConvention          : Standard
IsSecurityCritical         : False
IsSecuritySafeCritical     : False
IsSecurityTransparent      : True
ReturnType                 : System.Boolean
ReturnParameter            :
ReturnTypeCustomAttributes : System.Reflection.Emit.DynamicMethod+RTDynamicMethod+EmptyCAHolder
MemberType                 : Method
MethodImplementationFlags  : NoInlining
IsGenericMethodDefinition  : False
ContainsGenericParameters  : False
IsGenericMethod            : False
IsPublic                   : True
IsPrivate                  : False
IsFamily                   : False
IsAssembly                 : False
IsFamilyAndAssembly        : False
IsFamilyOrAssembly         : False
IsStatic                   : True
IsFinal                    : False
IsVirtual                  : False
IsHideBySig                : False
IsAbstract                 : False
IsSpecialName              : False
IsConstructor              : False
CustomAttributes           :
MetadataToken              :

Update 2 based on a comment by Mr Tree:

Invoke-RestMethod : The underlying connection was closed: An unexpected error occurred on a send.
At C:\Users\user\AppData\Local\Temp\ff47910e-fd8e-4be8-9241-99322144976a.ps1:13 char:1
+ Invoke-RestMethod -Uri $urlJSON -body $objAuth -method "Post"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
    + FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

I solved the mystery while troubleshooting another thing. The web server in question only supported TLS1.1 and TLS1.2. Powershell does not seem to support that by default.

To force TLS1.2 you can use this line:

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12