Solution : https://service.sap.com/sap/support/notes/1594907 (SAP Service marketplace login required)
Key words :
open profile \\<shared_directory>\<sid>_trx<instance>_<hostname>, user sapservice<sid>, install additional instance, windows event viewer, central instance host, logon failure reason, central instance, logon failure, unknown user, user domain
Related Notes :
| 1562325 | Post-installation configuration for multi-host landscape |
| 1258694 | TREX 7.1:Install TREX with Global File System (Windows) |