How to prevent Windows 10 from reverting skipped DHCPv6 IPv6 address? Or how to disable DHCPv6?

Question

My school allocated a /64 prefix IPv6 block to all my schoolmates, I want to fix the 64 bit suffix of my Windows 10 22H2 PC, so I executed the following PowerShell script to set my custom IPv6 address $ip the only one IP that is actually used for outgoing packages and succeeded.

Add a custom IPv6 address:

New-NetIPAddress -InterfaceAlias Wi-Fi -IPAddress $ip -PolicyStore ActiveStore -PrefixLength 64
Set-NetIPAddress -IPAddress $ip -SkipAsSource $False

Set all other public IPv6 addresses' SkipAsSource to $True to prevent them from being used for outgoing packages:

Get-NetIPAddress -InterfaceAlias Wi-Fi | ForEach-Object {
    if( ($_.AddressFamily.ToString() -eq "IPv6") -And ($_.IPAddress -ne $ip) -And ($_.PrefixOrigin.ToString() -ne "WellKnown") ){
        Set-NetIPAddress -IPAddress $_.IPAddress -SkipAsSource $True
    }
}

But after a few minutes, the IPv6 address whose PrefixOrigin is "Dhcp", its SkipAsSource became $False, which made my PC use the DHCP IPv6 address for outgoing packages. In order to find why, I executed the following PowerShell script to find the accurate time when the DHCP IPv6 address's SkipAsSource became $False:

$isChanged = $false
while( !$isChanged ){
    Start-Sleep 10
    Get-Date
    Get-NetIPAddress -InterfaceAlias "Wi-Fi" -AddressFamily IPv6 | ForEach-Object{
        if($_.PrefixOrigin -eq "Dhcp"){
            if($_.SkipAsSource -eq $False){
                $global:isChanged = $True
                Write-Host -ForegroundColor Red "Found it"
                break
            }else{
                Write-Host "Nothing wrong"
            }
        }
    }
}

The time span I found is between 2023-07-12 02:20:00 UTC+8 and 2023-07-12 02:20:10 UTC+8, then found the following system log whose timestamp is 2023-07-12 02:20:01 UTC+8 which maybe related.

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Netwtw04" />
    <EventID Qualifiers="16384">7003</EventID>
    <Version>0</Version>
    <Level>4</Level>
    <Task>0</Task>
    <Opcode>0</Opcode>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2023-07-11T18:20:01.5397220Z" />
    <EventRecordID>122318</EventRecordID>
    <Correlation />
    <Execution ProcessID="4" ThreadID="9152" />
    <Channel>System</Channel>
    <Computer>ComputerName</Computer>
    <Security />
  </System>
  <EventData>
    <Data>\Device\NDMP5</Data>
    <Data>Intel(R) Dual Band Wireless-AC 3165</Data>
    <Binary>0000080002003800000000005B1B00400000000000000000000000000000000000000000000000000000000000000000</Binary>
  </EventData>
</Event>

And the following two logs from Applications and Services Logs\Microsoft\Windows\Dhcp-Client\Microsoft-Windows-DHCP Client Events/Admin have the same timestamp. There is no log with the same or neighboring timestamp from Applications and Services Logs\Microsoft\Windows\Dhcp-Client\Microsoft-Windows-DHCPv6 Client Events/Admin:

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-Dhcp-Client" Guid="{15a7a4f8-0072-4eab-abad-f98a4d666aed}" />
    <EventID>50067</EventID>
    <Version>0</Version>
    <Level>4</Level>
    <Task>3</Task>
    <Opcode>57</Opcode>
    <Keywords>0x4000000000000000</Keywords>
    <TimeCreated SystemTime="2023-07-11T18:20:01.5559344Z" />
    <EventRecordID>6641</EventRecordID>
    <Correlation />
    <Execution ProcessID="2044" ThreadID="6392" />
    <Channel>Microsoft-Windows-Dhcp-Client/Admin</Channel>
    <Computer>sanfrancisco</Computer>
    <Security UserID="S-1-5-19" />
  </System>
  <EventData>
    <Data Name="NetworkHintString">SSID</Data>
    <Data Name="NetworkHint">SSID hex</Data>
    <Data Name="HWLength">6</Data>
    <Data Name="HWAddress">MAC address</Data>
  </EventData>
</Event>

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-Dhcp-Client" Guid="{15a7a4f8-0072-4eab-abad-f98a4d666aed}" />
    <EventID>50065</EventID>
    <Version>0</Version>
    <Level>4</Level>
    <Task>3</Task>
    <Opcode>55</Opcode>
    <Keywords>0x4000000000000000</Keywords>
    <TimeCreated SystemTime="2023-07-11T18:20:01.5559369Z" />
    <EventRecordID>6642</EventRecordID>
    <Correlation />
    <Execution ProcessID="2044" ThreadID="6392" />
    <Channel>Microsoft-Windows-Dhcp-Client/Admin</Channel>
    <Computer>sanfrancisco</Computer>
    <Security UserID="S-1-5-19" />
  </System>
  <EventData>
    <Data Name="NetworkHintString">SSID</Data>
    <Data Name="NetworkHint">SSID hex</Data>
    <Data Name="HWLength">6</Data>
    <Data Name="HWAddress">MAC address</Data>
  </EventData>
</Event>

So how to prevent the DHCP IPv6 address from being reverted? Or how to disable DHCPv6?

Answer 1

I found that I can disable DHCPv6 for a net card by Set-NetIPInterface -Dhcp Disable -InterfaceAlias Wi-Fi -AddressFamily IPv6. After executing that, my net card had only 2 public IPv6 addresses, respectively set by myself mannally and SLAAC. But even after I set the SLAAC IPv6's SkipAsSource as $True, it still reverted to $False hours after. Now I disabled SLAAC by netsh interface ipv6 set interface Wi-Fi routerdiscovery=disabled and my problem got solved completely as Windows have only one public IPv6 address.