Link Server Error - From SQL2008r2 to SQL2014
Please try specifying the @datasrc parameter when you create a linked server, e.g.

EXECUTE sp_addlinkedserver 
@server = N'server\SQL2014', 
@srvproduct=N'sql_server', @provider=N'SQLNCLI10', 
@datasrc = N'server\SQL2014'


The confusion may lie with the @server parameter being a descriptive name of the linked server to use in your code.  @datasrc is actually physical server name used by OLEDB to make the connection.