C # Connection string set timeout time

The timeout period has expired. Time out before the operation completes or the server is not responding "(Linq connection database, MySQL database)
The first type:
_db. Connect.connecttimeout = 500;//program error
Because the timeout property of Connect is read-only
_db.commandtimeout = 500; Normal operation at this time
The second type: (Simple test)
SqlConnection con = new SqlConnection ("server=.; Database=mydb;uid=sa;pwd=password; ") instead: SqlConnection con = new SqlConnection ("server=.; Database=mydb;uid=sa;pwd=password; Connect timeout=500 ")//seems to have no effect. Still running for 30 seconds to report timeout!

C # Connection string set timeout time