LAN Windows 11 24h2 Slow performance

[AHeyne]

What is the content of the constant/variable named "ODBC_DRIVER"?

More ideas:

Did you check the "SQL Server Configuration Manager" on your SQL Server?
Take a look into "SQL Server Network Configuration", choose your SQL Server instance and ensure TCP/IP is activated.
Then restart your SQL Server Instance Service and try again.

Could it be a DNS problem? For a test you could try to use the sql servers ip-address in the connection string instead of its name.

Do you have multiple sql server instances on the server? How about trying to use a fixed port for your instance and set this port in the connection string?

 

[The_Doc_Man]

However a minute later it went back to 30s load.

This comment didn't fully register with me at first, but... for most networks, the default network interface timeout for establishing a connection is 30 seconds. If you are getting frequent (regular) delays of 30 seconds then whatever step is waiting that long may be waiting on a network timeout. The fact that it works at all means it eventually takes an alternate network path that results in a good connection via that alternate path.

I would go back to your connection setup to check addresses. I would also look at the dynamic routing tables on affected PCs. Finally, I would locate the \etc folder to examine the hosts file, which is human-readable if a bit cryptic. It is possible to have multiple addresses for a host if that host has multiple network cards OR is accepting "aliased" traffic. Verify the addresses and verify that the routes to those addresses are correct. This could be caused by a connection having to use an aliased host name OR it could be forced to use an alternate route when the putative primary route fails to connect.

If you can do so in your environment, you want to open the CMD prompt so you can get to the PING command, ROUTE command, and a few other useful command-line utilities for network testing and configuration. You can type HELP utility-name or utility-name /H or utility-name ? to get help. One of those three will work, but not necessarily all three on the same utility. If you used the wrong help request, usually the utility will get snippy and tell you which one you should use.

ADDENDUM (TDM): If you ARE waiting for a connection, you can tell because the Windows Task Manager >> Peformance >> Network graph will show your system's normal network background for 30 seconds and then you'll get a sudden spike in network traffic.