Windows – SQL Server not working after upgrading windows 10 from windows 8.1

This question is quite old - hoping you solved your issue long before now... Assuming that you have not, I'd say to try the following:

1.) Check client xxx.xxx.x.81 to ensure that it has the proper ODBC drivers set-up for SQL Server (Control Panel -> type "ODBC" in the search box in the top right -> hit "Set up ODBC data sources..."

If not, set it up and try to reconnect. If they are set-up properly, move on to step 2...

2.) Connect from the client that is working and run a DBCC CHECKDB against "Database 28" to ensure that it's not a weird issue with the DB itself

Microsoft says that event error 904 is not logged... so, you'll have to set something up manually to get feedback on the error from the server.

3.) Finally, (this may go without saying considering the age of the post) try upgrading the server to a newer, supported version (if you have not already.) Also, update your SSMS version.

Report back with any progress or further issues?

As asked by the QA, i'm adding my comment as an answer:

Repairing microsoft .net 4.0 can be the problem solver; if you run out of options, you can also use another local account to install it, then relog into your current account.