What does QuickBooks Error H505 mean?

https://quickbookhelpdesk.com/blog/fix-quickbooks-error-h505/

H505 generally means QuickBooks cannot establish the required multi-user connection between a workstation and the computer hosting the company file. QuickBooks Error H505 usually occurs when QuickBooks cannot establish the connection needed for Multi-User Mode. Incorrect hosting settings are one of the main things to check, especially when a workstation has accidentally been configured to host the company file.