Today I was trying to connect to SQL Server from my OSx Mac and I was getting Unable to connect: Adaptive Server is unavailable or does not exist.
I was able to connect to another sql server in the same farm from laptop.
Found out by default –>
TCP connectivity is disabled for SQL Server.
Microsoft SQL Server 2008 R2 > Configuration Tools > SQL Server Configuration Manager > SQL Server Network Configuration > Protocols for MSSQLSERVER
Protocol Name: TCP/IP (Enable)
Thats all :))