This is an existing installation that was working. We had this problem on Friday and restarted everything thing and it was ok. It has happened before on restarts.
I can connect to the sql server by name on sql studio mgr from the same machines. BUt the MS Access App throws error:
SQL Server Error: -1
[Microsoft][SQL Server Native Client 11.0] SQL Server Network Interfaces: Error Locating Server/Instances Specified[xFFFFFFFF]
SQL State: 108001'
Again this was all working this morning and for years before.