Solution : https://service.sap.com/sap/support/notes/1496606 (SAP Service marketplace login required)
Summary : 
      To manually set the gateway host in transaction RSPRECALCADMIN beyond the system's default hostname, users need to install specific Support Packages for SAP NetWeaver BW or implement the correction via transaction SNOTE. Additionally, SAP_RSADMIN_MAINTAIN report should be used to make RSPRECALCADMIN_GWHOST_EDITABLE with value 'X'. The relevant SAP Notes and Support Packages for multiple versions of SAP NetWeaver BW specify required version details. Manual skips in urgent scenarios are possible, supported by further instructions on implementing corrections before the full release of listed Support Packages. Check SAP Note 875986 for details on using SNOTE.
Key words : 
prerequisites missing functionality solution install, software component   sap_bw                        business inform, sap router string reason, component type rfcgwhost, sapbwnews nw bw 7, manual pre-implement, data type rsr_precalc_admin_server, sap netweaver bw 7, sap nw bw7, 01 bw abap sp08
Related Notes : 
       
| 1471463 | SAPBWNews NW BW 7.01 ABAP SP08 | 
| 1468668 | SAPBWNews NW7.0 BW ABAP Support Package 25 | 
| 1450990 | SAPBWNews NW BW 7.02 ABAP SP05 | 
| 1424130 | PrecalcServer: New administration transaction RSPRECALCADMIN | 
| 1392433 | SAPBINews NW7.11 BW ABAP Support Package 05 |