1. Install Powershell 7 Release 5 x64 on a up-to-date Windows 10 Computer
2. Run Powershell 7
3. Run the following script...

$ComputerNames = "Computer1","Computer2", "Computer3"
$ComputerNames | ForEach-Object -Parallel {
     Restart-Computer -ComputerName $_ -Force -Wait -Timeout 1800
}
4. Wait the allotted Timeout period of 30 minutes.

Where Computer1-3 are test computers on the same network.

Paul Higin Tested this and commented in another tread;

"This appears to be an error in the Restart-Computer cmdlet. When I run it alone in the latest
preview build, it restarts the remote computer as expected, but never returns and eventually 
crashes PowerShell. I get the same behavior when running it within a foreach -parallel 
script block.

This appears to have nothing to do with foreach -parallel, except that foreach -parallel doesn't
currently support progress data (by design) and so there is no indicator of how the computer
restart is proceeding.

I feel this Issue should be closed and two new issues open:
a. Restart-Computer -cn -Force -Wait -Timeout is broken in latest build.
b. ForEach -Parallel to support progress data stream (not sure how this would work and it would 
be a new feature request anyway)."
--




 

The remote computer will reboot and the script will continue without error.

The computers reboot, but PowerShell never reconnects to them.

After 30 Minutes, the following errors are received;

Restart-Computer: Failed to restart the computer Computer1 with the following error
 message: The computer did not finish restarting within the specified time-out period..
Restart-Computer: Failed to restart the computer Computer2 with the following error
 message: The computer did not finish restarting within the specified time-out period..
Restart-Computer: Failed to restart the computer Computer3 with the following error
 message: The computer did not finish restarting within the specified time-out period..

Name                           Value
----                           -----
PSVersion                      7.0.0-preview.5
PSEdition                      Core
GitCommitId                    7.0.0-preview.5
OS                             Microsoft Windows 10.0.17763
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0