why the script shows "Couldn't connect to remote machine"

I have a script to remove a specific patch I installed several days ago from a list of computers. The code is as below:

function Uninstall-Hotfix {
[cmdletbinding()]
param(
$computername = $env:computername,
[string] $HotfixID
)            

$hotfixes = Get-WmiObject -ComputerName $computername -Class Win32_QuickFixEngineering | select hotfixid            

if($hotfixes -match $hotfixID) {
    $hotfixID = $HotfixID.Replace("KB","")
    Write-host "Found the hotfix KB" + $HotfixID
    Write-Host "Uninstalling the hotfix"
    $UninstallString = "cmd.exe /c wusa.exe /uninstall /KB:$hotfixID /quiet /norestart"
    ([WMICLASS]"\\$computername\ROOT\CIMV2:win32_process").Create($UninstallString) | out-null            

    while (@(Get-Process wusa -computername $computername -ErrorAction SilentlyContinue).Count -ne 0) {
        Start-Sleep 3
        Write-Host "Waiting for update removal to finish ..."
    }
write-host "Completed the uninstallation of $hotfixID"
}
else {            

write-host "Given hotfix($hotfixID) not found"
return
}            

}



$myComputers = Get-Content "c:\PowerShell Scripts\computers_needremove.txt"
foreach ($computer in $myComputers) {
 Uninstall-HotFix -ComputerName $computer -HotfixID KB3097877
}

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When I ran this script, it uninstalled the hotfix but in the progress of running it, it gave me error message like below, could you please help me with this:

PS C:\PowerShell Scripts> .\patch_remove.ps1
Given hotfix(KB3097877) not found
Given hotfix(KB3097877) not found
Found the hotfix KB + 3097877
Uninstalling the hotfix
Get-Process : Couldn't connect to remote machine.
At C:\PowerShell Scripts\patch_remove.ps1:18 char:14
+     while (@(Get-Process wusa -computername $computername -ErrorAction SilentlyC ...
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Get-Process], InvalidOperationException
    + FullyQualifiedErrorId : System.InvalidOperationException,Microsoft.PowerShell.Commands.GetProcessCommand

Completed the uninstallation of 3097877
Found the hotfix KB + 3097877
Uninstalling the hotfix
Get-Process : Couldn't connect to remote machine.
At C:\PowerShell Scripts\patch_remove.ps1:18 char:14
+     while (@(Get-Process wusa -computername $computername -ErrorAction SilentlyC ...
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Get-Process], InvalidOperationException
    + FullyQualifiedErrorId : System.InvalidOperationException,Microsoft.PowerShell.Commands.GetProcessCommand

Completed the uninstallation of 3097877
Found the hotfix KB + 3097877
Uninstalling the hotfix
Get-Process : Couldn't connect to remote machine.
At C:\PowerShell Scripts\patch_remove.ps1:18 char:14
+     while (@(Get-Process wusa -computername $computername -ErrorAction SilentlyC ...
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Get-Process], InvalidOperationException
    + FullyQualifiedErrorId : System.InvalidOperationException,Microsoft.PowerShell.Commands.GetProcessCommand