A drive letter that disappears at every logon usually has no stored credential or no persistent flag. Store the credential in Credential Manager, map with net use /persistent:yes and check the registry key Windows really uses.
Use **cmdkey** to store the credential, then **net use Z: \\server\share /persistent:yes**. The pair is what makes the letter return after a reboot, and **HKCU\Network\Z** is the key Explorer reads at sign-in.
**Test-Path** on the UNC path fails fast and tells you whether the problem is the network or the mapping. **net view** lists what the server publishes, which catches a mistyped share name.
net view \\nas01
Test-Path \\nas01\projects
Resolve-DnsName nas01**cmdkey** writes the password into the user's credential vault, so no prompt appears at sign-in. The target name must match the server exactly as the mapping uses it.
cmdkey /add:nas01 /user:nas01\backup /pass:Str0ngPass
cmdkey /list:nas01Without **/persistent:yes** the mapping lives only in the current session. **Get-SmbMapping** shows the status and whether the entry is remembered.
net use Z: \\nas01\projects /persistent:yes
Get-SmbMapping
Get-ChildItem Z:\ | Select-Object -First 5 NameA persistent mapping is a value under **HKCU\Network** named after the drive letter. If the key is missing, the mapping was created with the persistent flag off, no matter what the dialog claimed.
Get-ItemProperty HKCU:\Network\Z
Get-ChildItem HKCU:\Network | Select-Object PSChildName,RemotePathElevated processes get a separate logon session and cannot see mappings made by the normal one. **EnableLinkedConnections** lets both share the same drive letters, which is the usual cure for a red cross on boot.
reg add "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" /v EnableLinkedConnections /t REG_DWORD /d 1 /f
taskkill /f /im explorer.exe
start explorer.exe**net use /delete** drops the letter and the stored entry; the credential stays in the vault until it is deleted separately. A ghost letter usually means the persistent value survived.
net use Z: /delete /y
cmdkey /delete:nas01
Get-SmbMapping
Get-ChildItem HKCU:\Network -ErrorAction SilentlyContinueThe credential is missing or the server answers after Explorer starts. Sign in, open the drive once, and confirm cmdkey /list:nas01 returns an entry with the right user.
The stored target name does not match. cmdkey stores per server, so nas01 and nas01.domain.local are two entries; map with the name you stored.
Network path not found. Check Resolve-DnsName, then try the IP address to rule out name resolution before blaming the share.
This is the linked-connection split. Set EnableLinkedConnections as in step 5 and restart Explorer.
Yes. A mapping gives a drive letter and lives in the session; a network location is a shortcut that survives without a letter but cannot be used by older programs that expect a path like Z:\.
No. HKCU\Network and the credential vault are per user. Each account needs its own cmdkey entry and its own net use call.
Always. A UNC path needs no mapping at all and works in scripts without any logon state, which is why scheduled tasks should use \\server\share rather than Z:\.
Run net use Z: /delete /y to drop the letter and cmdkey /delete:nas01 to remove the saved credential. Delete the EnableLinkedConnections value if you added it, then restart Explorer.
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