QuickBooks multi-user mode is a convenient feature that allows multiple users to access and work on the same company file simultaneously. However, there might be instances when you encounter issues with the multi-user mode not working as expected. Here are some troubleshooting steps to consider:

Verify network connectivity: Ensure that all computers are connected to the same network and can communicate with each other. Check network cables, routers, and firewalls to rule out any potential connectivity issues.

Check hosting settings: In the QuickBooks Desktop application, go to the File menu and select "Utilities." Make sure that the "Host Multi-User Access" option is turned on for the computer hosting the company file. Disable hosting on other computers.

Restart QuickBooks Database Server Manager: Open the Windows Start menu, search for "QuickBooks Database Server Manager," and open it. Click on the "Scan Folders" tab and add the folder containing the company file. Click "Scan" to refresh the server manager.

Test with a sample company file: Create a new sample company file and attempt to open it in multi-user mode. If it works, the issue might lie with the original company file.

Update QuickBooks: Ensure that all computers have the latest QuickBooks updates installed. Go to the Help menu and select "Update QuickBooks."

Disable antivirus and firewall temporarily: Temporarily disable antivirus and firewall software on all computers to check if they are causing any conflicts with the multi-user mode.