Script to mass disable sync for Office 365 Groups

I took a stab at this using the scripts already created by jcgonzalezmartin and Brent Ellis along with the site iteration scripts here.  This will set the Offline Client Availability at the web level initially for the site you enter and give you the option to do all subsites (I edited the original to include all levels of subsites based on this super handy script here and not just level 1).  I tested this on Group and Classic sites.  It certainly could be cleaned up a bit and be enhanced to support things like .csv input and probably overall more optimized.  

Add-Type -Path "C:\temp\microsoft.sharepointonline.csom.16.1.6008.1200\lib\net45\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\temp\microsoft.sharepointonline.csom.16.1.6008.1200\lib\net45\Microsoft.SharePoint.Client.runtime.dll"

$siteUrl = Read-Host -Prompt "Enter Site Collection URL"
$username = Read-Host -Prompt “Enter username”
$password = Read-Host -Prompt “Enter password” -AsSecureString
$subwebcheck = Read-Host -Prompt "Do you want to process subsites? (Y/N)"

# Generate ClientContext function so we can reuse
function GetClientContext($siteurl, $username, $password) {
     $ctx = New-Object Microsoft.SharePoint.Client.ClientContext($siteurl) 
     $credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($username, $password) 
     $ctx.Credentials = $credentials
     return $ctx
}

$ctx = GetClientContext $siteurl $username $password

if ($ctx.ServerObjectIsNull.Value) { 
    Write-Host "Unable to connect to: '$siteUrl'" -ForegroundColor Red
} else {
    Write-Host "Connected to: '$($siteUrl)'" -ForegroundColor Green 

    $rootWeb = $ctx.Web
    $ctx.Load($rootWeb)
    $ctx.ExecuteQuery()

    # update root site
    Write-Host $rootWeb.Url "is being updated to exclude from offline clients"
    $rootWeb.ExcludeFromOfflineClient=$true
    $rootWeb.Update()
    $ctx.Load($rootWeb)
    $ctx.ExecuteQuery()
    Write-Host "ExcludeFromOfflineClient is now" $rootWeb.ExcludeFromOfflineClient "for the site:" $rootWeb.Url -ForegroundColor Green
       
    if ($subwebcheck -eq "Y") {
        
        # work with subsites
        Write-Host "Processing subsites..." -ForegroundColor Yellow
        $childWebs = $rootWeb.Webs
        $ctx.Load($childWebs)
        $ctx.ExecuteQuery()
        foreach ($childWeb in $childWebs)
        {
            processsubsites $childWeb.url
        }
    }

    # function to loop through subsites and setting values
    function processsubsites ($siteurl){
        $ctx = GetClientContext $siteurl $username $password
        $rootWeb = $ctx.Web
        $childWebs = $rootWeb.Webs
        $ctx.Load($rootWeb)
        $ctx.Load($childWebs)
        $ctx.ExecuteQuery()

        # perform update
        if($rootWeb.WebTemplate -ne "APP"){
            Write-Host $rootWeb.Url "is being updated to exclude from offline clients"
            $rootWeb.ExcludeFromOfflineClient=$true
            $rootWeb.Update()
            $ctx.Load($rootWeb)
            $ctx.ExecuteQuery()
            Write-Host "ExcludeFromOfflineClient is now" $rootWeb.ExcludeFromOfflineClient "for the site:" $rootWeb.Url -ForegroundColor Green
        }

        # loop subsites of subsites
        foreach ($childWeb in $childWebs)
        {           
            processsubsites $childWeb.url
        }
    }


}

To note, Setting this property to true does not disable synchronization. Instead, it represents a recommendation to the client not to attempt synchronization. This info is pulled from here. 

Looks like it was still reading from my older version of CSOM, but got it working quick and dirty:

Add-Type -Path "C:\SP\Microsoft.SharePointOnline.CSOM.16.1.6112.1200\lib\net45\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\SP\Microsoft.SharePointOnline.CSOM.16.1.6112.1200\lib\net45\Microsoft.SharePoint.Client.runtime.dll"

# SharePoint Authentication
$username = "<username here>"
$password = '<password here>'
$securePassword = ConvertTo-SecureString $Password -AsPlainText -Force 
$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($username, $securePassword) 

Write-Host "Fetching O365 Groups" -ForegroundColor Yellow
$o365Groups = get-unifiedgroup
$count = 0

foreach($group in $o365Groups){
    $count++
    Write-Host ""
    Write-Host $count $group.DisplayName $group.primarysmtpaddress -ForegroundColor Cyan

    $clientContext = New-Object Microsoft.SharePoint.Client.ClientContext($group.SharePointSiteUrl) 
    $clientContext.Credentials = $credentials 

    if ($clientContext.ServerObjectIsNull.Value) { 
        Write-Host "Unable to connect to: '$url'" -ForegroundColor Red
    } else {
        Write-Host "Connected to: '$($group.SharePointSiteUrl)'" -ForegroundColor Green 

        $Libraries = $clientContext.Web.Lists
        $clientContext.Load($Libraries)
        $clientContext.ExecuteQuery()

        foreach($Library in $Libraries){
            if($Library.BaseTemplate -eq "101"){
                Write-Host $Library.Title
                $Library.ExcludeFromOfflineClient=$true
                $Library.Update()
            }
        }

    }

}