Hi Thierry Joel Meli Tchinda •,
Please check below and share information from your end to understand the issue better:
1). If issue is due to Server Configuration, please make sure in your Linked Service, Server Name is correctly given like shown below:
Same as shown in SSMS for your on premise server:
2). Secondly, if issue is related to User, check the User through which you are connecting is Active and has required settings enabled to login in ADF:
Go to Security Folder at Server level then Open Properties.
Go to Server Roles and check "sysadmin" as that might help.
Also, got to "Status" section and make sure SQL Server auth is enabled.
3). This could also be a cause that your SQL Service needs a Restart.
Please make sure your on-premise SQL Server Services is at Running in SQL Server Configuration Manager and Network Configuration for your Database has Protocols Enabled:
Try restart of the Services:
Let us know if above helped or you have some information to share so that we can further troubleshoot.
Thanks