вот этот Connection работает вне SQL Server
[oledb]
; Everything after this line is an OLE DB initstring
Provider=IBMDA400.DataSource.1;Password="";Persist Security Info=True;User ID=tomc;Data Source=xxx.xxx.xxx.xxx;Protection Level=None;Initial Catalog="";Transport Product=Client Access;SSL=DEFAULT;Force Translate=65535;Default Collection="";Convert Date Time To Char=TRUE;Catalog Library List=QGPL;Cursor Sensitivity=3

Не могу создать работающий linked server
sp_addlinkedserver
@server='AS400_OLE',
@srvproduct='IBMDASQL.DataSource.1',
@provider='IBMDA400',
@datasrc='xxx.xxx.xxx.xxx',
@provstr='Protection Level=None;Initial Catalog="";Transport Product=Client Access;SSL=DEFAULT;Catalog Library List=QGPL;Cursor Sensitivity=3',
@location='QGPL',
@catalog='' ;

Msg 7399, Level 16, State 1, Line 8
The OLE DB provider "IBMDA400" for linked server "AS400_OLE" reported an error. Access denied.
Msg 7350, Level 16, State 2, Line 8
Cannot get the column information from OLE DB provider "IBMDA400" for linked server "AS400_OLE".