Guides / Mapped network drive disconnected or red X in File Explorer

Part of: Work PC problems: updates, apps, printers and remote access

Last reviewed 6 Oct 2026 · By Harry

Mapped network drive disconnected or red X in File Explorer

Mapped drive shows a red X, asks for credentials, or will not reconnect after login? VPN, DNS, credentials and SMB checks for shared drives at work.

The S: drive has a red X. Double-clicking it says An error occurred while reconnecting or asks for a password nobody remembers setting. This is a classic hybrid-working ticket: the drive was mapped in the office, and now the laptop is at home, or it woke from sleep before the network was ready. The file server is almost always fine. Work out whether the PC can reach it.

First: where is the share?

• On-premises file server (\\fileserver\share). Needs the office LAN or VPN. No public status page will help.
• Azure Files. Needs SMB port 445 to Azure, which many home ISPs and some offices block. Check Azure status only if several sites fail together.
• SharePoint mapped as a drive via WebDAV. This is fragile and unsupported for heavy use; sync the library with OneDrive instead.

User checks

1. Red X after sleep or login. Windows shows the red X before it tries to reconnect. Double-click the drive. If it opens, there is nothing wrong — Windows was just slow.
2. Connect the VPN. At home, the server is unreachable without it. Connect, wait thirty seconds, then open the drive. If internal sites also fail, read VPN connected but no internet.
3. Try the full path. Press Win+R and type the UNC path, for example \\fileserver.company.local\finance. If the full name works and the short name does not, it is DNS suffix search.
4. Try the IP address. \\10.0.0.20\finance. If the IP works and names fail, DNS is the fault.
5. Saved credentials. Open Credential Manager → Windows Credentials. Remove old entries for the file server, especially after a password change, then reconnect and enter current credentials once.
6. Disconnect and remap. Right-click the drive → Disconnect. Then remap with the path IT documented. If the drive came from Group Policy or Intune, sign out and back in instead, so policy remaps it correctly.

Tests IT will ask for

• net use — lists mapped drives and their status (OK, Disconnected, Unavailable).
• Test-NetConnection fileserver -Port 445 — proves whether SMB is reachable. False over home broadband but true on VPN means the VPN or firewall is in play.
• nslookup fileserver — confirms the name resolves to the internal IP, not a public or wrong address.
• klist — shows Kerberos tickets. If there is no ticket for cifs/fileserver, authentication is falling back or failing.

Admin-level causes

• Drive maps run before the network. Group Policy Preferences drive maps at logon fail when Wi-Fi or VPN connects later. Use Item-level targeting, the Always wait for the network policy, or reconnect scripts triggered when the VPN connects. Always-on VPN with device tunnel solves this properly.
• Password changes and cached credentials. Users who change passwords off-network keep the old cached credential. Kerberos then fails against the file server until they connect to the domain network and lock/unlock.
• SMB1 disabled. Very old NAS boxes only speak SMB1, which modern Windows disables. Update or replace the NAS; do not re-enable SMB1.
• SMB signing and guest access. Recent Windows builds require SMB signing in more scenarios and block insecure guest logons. Cheap NAS devices with guest shares break after updates. Configure a proper account on the NAS.
• Port 445 blocked. Many ISPs block outbound 445. Azure Files over the internet needs it open, or a VPN / Private Endpoint.
• Server-side. If nobody in the office can open the share, check the server: disk full, service stopped, DFS namespace target offline, or a certificate/time problem breaking Kerberos.

When to escalate

Escalate to the server or network team when several users, including people in the office, cannot open the share. Escalate to the VPN owner when only remote users fail and port 445 tests fail through the tunnel. One laptop with stale saved credentials is a five-minute fix.

Related status pages

• Microsoft Entra ID
• Microsoft Azure
• Microsoft 365

Related guides

• VPN connected but no internet or can't reach internal sites
• Remote Desktop (RDP) won't connect at work
• Wi-Fi keeps dropping on a work laptop

FAQ

Why does my mapped drive show a red X?

Windows shows a red X before it reconnects, after sleep, or when the server is unreachable. Double-click it first. At home, connect the VPN before opening the drive.

Why does the network drive ask for a password?

Saved credentials are often out of date after a password change. Remove old entries in Credential Manager and reconnect with your current work credentials.

How do I reconnect a mapped drive?

Connect to the office network or VPN, then double-click the drive. If it still fails, disconnect and remap it, or sign out and back in if IT maps drives by policy.

Is a disconnected network drive an outage?

Only if colleagues in the office also cannot open it. If they can, the server is up and your connection, VPN, DNS or credentials need fixing.