Windows Server SMB Port 445 Troubleshooting Guide

!Issue

Troubleshoot SMB file share connectivity by checking TCP 445, Windows Firewall, DNS, authentication and share permissions.

✓Solution

01 Test TCP 445

★Recommendations

06 Validate mapping Test the UNC path directly and then remap the drive if the environment uses persistent mappings.

From the client, use Test-NetConnection <server> -Port 445 to determine whether the SMB service is reachable.

Test TCP 445

Confirm the server name resolves to the correct IP address and that stale DNS does not send clients to an old host.

Verify Windows Firewall and network firewalls allow SMB where the environment requires it. Avoid opening SMB broadly to untrusted networks.

Confirm LanmanServer is running and that the target share exists.

Evaluate both share and NTFS permissions and confirm the user is authenticating to the intended server.

Test the UNC path directly and then remap the drive if the environment uses persistent mappings.

Continue with practical infrastructure troubleshooting, PowerShell scripts and operational runbooks.