How to Troubleshoot Network License Borrowing & Timeout Errors (FlexNet / GLS)?
License borrowing failures occur due to firewall port blocking (TCP 27000–27009), incorrect server system clocks, or client borrowing caps. Resolve by whitelisting lmgrd and vendor daemons in Windows Firewall, synchronizing NTP time, and editing gstar.opt parameters.
Tested on FlexNet Publisher 11.19 / GstarCAD GLS Network License Server on Windows Server 2025.
FlexNet Publisher License Administration Guide, RFC 793 (TCP).
Gstarcademy Diagnostics Board · Audited
Suzhou Gstarsoft Co., Ltd. (SSE: 688657)
Direct Diagnostic Solution & Protocol
Quick Resolution: License borrowing failures occur due to firewall port blocking (TCP 27000–27009), incorrect server system clocks, or client borrowing caps. Resolve by whitelisting lmgrd and vendor daemons in Windows Firewall, synchronizing NTP time, and editing gstar.opt parameters.
Step-by-Step Engineering Execution
Step 1: Check Daemon Port Communication
FlexNet requires two open ports: the license manager daemon (default TCP 27000) and the vendor daemon (random port if unassigned). In the license file, assign a fixed vendor port: VENDOR gstar port=27005.
Step 2: Whitelist Ports in Windows Defender Firewall
On the license server, open Windows Firewall with Advanced Security. Create Inbound Rules opening TCP ports 27000 and 27005 for domain traffic.
Step 3: Audit Server/Client Time Drift
If the client workstation clock differs from the server clock by more than 10 minutes, FlexNet rejects borrow requests as potential cryptographic replay attacks. Synchronize with domain NTP.
Step 4: Clear Stale Borrow Registry Keys
On the client PC, if a borrowed license fails to return, launch GstarCAD License Manager as Administrator, click 'Return License', or clear stale borrow tokens under HKEY_CURRENT_USER\Software\FLEXlm License Manager.
Cross-Disciplinary Verification & Support
Underlying Kernel Mechanics & Automated Prevention Protocol
To permanently prevent recurrence of How to Troubleshoot Network License Borrowing & Timeout Errors (FlexNet / GLS)? across enterprise project directories, CAD managers must understand how the underlying DWG object database (AcDbDatabase / GcDbDatabase) and graphics display pipeline manage entity handles, symbol tables, and external dependencies:
| Diagnostic Command / Variable | Recommended Production Value | Engineering Function & Impact |
|---|---|---|
| AUDIT / RECOVERALL | Fix Errors = Yes (Y) |
Validates B-tree symbol tables, repairs orphaned dictionary handles, and heals nested Xrefs. |
| -PURGE → Regapps (R) | Verify Each = No (N) |
Strips thousands of unreferenced third-party Registered Application IDs that bloat DWG memory. |
| GRAPHICSCONFIG | Hardware Acceleration = ON | Verifies DirectX 11/12 or OpenGL GPU driver allocation and clears corrupted display cache buffers. |