SQL Server 2008 OLE DB Connection fails from outside

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SQL-Server

SQL-Server-2008

I have a working SQL Server 2008 R2 Express installed on a Windows 2008 server on a cloud machine. All type of connections (ado.net, nhibernate etc.) from several client applications works fine except the OLEDB one. SQL Native Client also works fine.

When I tried to connect from the server locally and as a data source write the instance name, everything was OK. But from outside, I had the problem or also if I write wan ip or dns I had the problem also from local.
-- works perfect from everywhere
Provider=SQLNCLI10;Data Source=mntek.no-ip.org;User ID=xxx;Password=xxx;

-- does not work from anywhere
Provider=SQLOLEDB.1;Data Source=mntek.no-ip.org;User ID=xxx;Password=xxx;

-- works only from local
Provider=SQLOLEDB.1;Data Source=flz001\sqlexpress;User ID=xxx;Password=xxx;


Error: [DBNETLIB][ConnectionOpen (Invalid Instance()).Invalid connection.
-- works perfect with ado.net
Data Source=mntek.no-ip.org;User ID=xxx;Password=xxx

Some other client applications (not mine) was written with oledb connection so I need them to connect the db with oledb provider.

Any ideas?

Regards, Mert

[edit]SHOUTING removed - OriginalGriff[/edit]