Invoke-WebRequest command fails only when run as script - powershell

Question

I have this function in a powershell script to deploy a war file to a tomcat server. Similar functions for the other tomcat commands (stop, undeploy, list, etc) work fine. When I run the script from a shell it works. When I run the script from the Jenkins Powershell plugin it fails.
Function DeployTomcatWebApp([PSCredential]$cred, [string]$server, [string]$app)
{
Write-Host "Deploying $app"
$uri = $server+"/manager/text/deploy?path=/$app&update=true"
$warpath = ($pwd).path + "/$app/build/dev/$app.war"
$r = Invoke-WebRequest -Uri $uri -Credential $cred -InFile $warpath -UseBasicParsing -Verbose -Debug -Method PUT -TimeoutSec 30000 -DisableKeepAlive
Write-Host $r.Content
Return $r
}
The Console Log shows
Deploying DERF
D:\Jenkins\workspace\JenkinsTest_2_AD_DERF\DERF\build\dev\DERF.war
http://mytomcat:8080/manager/text/deploy?path=/DERF&update=true
VERBOSE: PUT http://mytomcat:8080/manager/text/deploy?path=/DERF&update=true with -1-byte payload
Invoke-WebRequest : The underlying connection was closed: An unexpected error occurred on a send.
At C:\Users\<jenkinsuser>\AppData\Local\Temp\jenkins1024175502034764284.ps1:49 char:10
+ $r = Invoke-WebRequest -Uri $uri -Credential $cred -InFile $warpa ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-WebRequest], WebExc
eption
+ FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeWebRequestCommand
The Jenkins Powershell plugin extracts the script from the jenkins job and create the .ps1 file in Local/Temp and executes the script by calling
powershell -NonInteractive -ExecutionPolicy Bypass <tempscriptname>
I am stumped and looking for any insight to debugging this.