From the event sequence, we observe a clear pattern of network instability during critical authentication phases:

1:25:57 - Network link disconnected (E1kexpress 27)
1:25:58 - LDAP call fails (0ms timeout)
1:25:59 - Link restored (1Gbps full duplex)
1:26:00 - Link drops again
1:26:05 - Link restored
1:26:18 - Successful DC discovery (2918ms)

The E1kexpress 27 errors point to Intel 82567LM-3 NIC driver issues. Let's verify driver settings via PowerShell:

# Check NIC advanced properties
Get-NetAdapterAdvancedProperty -Name "Ethernet" | 
Where-Object {$_.DisplayName -match "Energy|Power"} |
Format-Table -AutoSize

# Output should show:
# DisplayName                     DisplayValue  
# -----------                     ------------
# Energy Efficient Ethernet       Disabled
# Green Power                     Disabled

Create a registry fix to handle intermittent connectivity:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
"GpNetworkStartTimeoutPolicyValue"=dword:0000003c
"SyncForegroundPolicy"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System]
"SlowLinkDetectEnabled"=dword:00000000

This PowerShell script helps diagnose DC location issues:

function Test-DiscoveryLatency {
    param($domain = $env:USERDNSDOMAIN)
    
    $results = @()
    1..10 | ForEach-Object {
        $sw = [System.Diagnostics.Stopwatch]::StartNew()
        $dc = [System.DirectoryServices.ActiveDirectory.DomainController]::FindOne(
            (New-Object System.DirectoryServices.ActiveDirectory.DirectoryContext(
                [System.DirectoryServices.ActiveDirectory.DirectoryContextType]::Domain,
                $domain))
        )
        $sw.Stop()
        
        $results += [PSCustomObject]@{
            Attempt = $_
            DCName = $dc.Name
            Latency = $sw.ElapsedMilliseconds
            Timestamp = (Get-Date).ToString("HH:mm:ss.fff")
        }
    }
    
    $results | Export-Csv -Path "DC_Discovery_Latency.csv" -NoTypeInformation
    return $results
}

Check for TCP chimney offloading issues that may cause intermittent drops:

netsh int tcp show global
# Expected output:
# TCP Global Parameters
# ----------------------------------------------
# Receive-Side Scaling State          : enabled
# Chimney Offload State               : disabled
# NetDMA State                        : enabled

The WMI error suggests broken event subscriptions. Recreate the WMI repository:

net stop winmgmt
cd /d %windir%\system32\wbem
ren repository repository.old
net start winmgmt
for /f %s in ('dir /b /s *.mof *.mfl') do mofcomp %s

Implement secondary DNS resolution for DC discovery:

# Configure DNS client failover settings
Set-DnsClient -InterfaceIndex (Get-NetAdapter).ifIndex 
    -ConnectionSpecificSuffix "corp.ourdomain.edu" 
    -UseSuffixWhenRegistering $true 
    -RegisterThisConnectionsAddress $true

# Set SRV weight priority
Add-DnsClientNrptRule -Namespace ".ourdomain.edu" 
    -NameServers "dc1.ourdomain.edu","dc2.ourdomain.edu" 
    -DAEnable $true 
    -DAQueryInterval 15

For NICs showing frequent link drops:

# Check cable/port errors
Get-NetAdapterStatistics -Name "Ethernet" | 
Select-Object Name,ReceivedErrors,ReceivedDiscards,SentErrors,SentDiscards

# Validate auto-negotiation
Get-NetAdapterAdvancedProperty -Name "Ethernet" |
Where-Object {$_.DisplayName -match "Speed|Duplex"} |
Select-Object DisplayName,DisplayValue

From analyzing your event logs, I'm seeing a clear pattern of network interface instability during boot and logon sequences. The Intel® 82567LM-3 NIC appears to be cycling between connected/disconnected states during critical authentication phases:

1:25:57 - Network link disconnected (Event ID 27)
1:25:59 - Link established at 1Gbps full duplex  
1:26:00 - Network link disconnected again
1:26:05 - Link re-established at 1Gbps

The name resolution timeouts (1:26:08 timestamp) indicate DNS queries aren't being handled reliably during these network flaps. Try adding these registry tweaks to optimize DNS client behavior:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters]
"MaxCacheTtl"=dword:00000258
"MaxNegativeCacheTtl"=dword:00000000
"NetFailureCacheTime"=dword:00000000
"NegativeSOACacheTime"=dword:00000000
"QueryIpMatching"=dword:00000001

The 2-3 second DC discovery times are excessive for a gigabit network. Implement these GPO changes:

1. Enable Computer Configuration → Administrative Templates → System → Group Policy → Configure Group Policy slow link detection with threshold=500000 (500kbps)
2. Disable unused Group Policy extensions
3. Add registry key to prevent processing delays:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System]
"SyncMachinePolicyTimeout"=dword:0000003c
"SyncForegroundPolicyTimeout"=dword:0000003c

The Intel 82567LM has known issues with Windows 7 power states. Create a PowerShell script to apply these settings:

# Disable power saving features
Set-NetAdapterAdvancedProperty -Name "*" -DisplayName "Energy Efficient Ethernet" -DisplayValue "Disabled"
Set-NetAdapterAdvancedProperty -Name "*" -DisplayName "Green Ethernet" -DisplayValue "Disabled"
Set-NetAdapterPowerManagement -Name "*" -WakeOnMagicPacket Off -WakeOnPattern Off -DeviceSleepOnDisconnect Disabled

# Set static speed/duplex (temporarily for testing)
Set-NetAdapterAdvancedProperty -Name "*" -DisplayName "Speed & Duplex" -DisplayValue "1.0 Gbps Full Duplex"

# Disable IPv6 offloading
Set-NetAdapterAdvancedProperty -Name "*" -DisplayName "IPv6 Checksum Offload" -DisplayValue "Disabled"
Set-NetAdapterAdvancedProperty -Name "*" -DisplayName "TCP/IPv6 Checksum Offload" -DisplayValue "Disabled"

Ensure your AD sites properly reflect network topology. Run this to verify:

nltest /dsgetsite
nltest /dsgetdc:yourdomain.com
repadmin /showrepl
dcdiag /test:netlogons /test:services /test:replications

If using logon scripts, implement parallel execution with this pattern:

@echo off
start "" /B script1.cmd
start "" /B script2.vbs
start "" /B powershell.exe -ExecutionPolicy Bypass -File script3.ps1
timeout /t 10 >nul
:wait
tasklist | find /i "cmd.exe" >nul && (
    timeout /t 1 >nul
    goto wait
)