Where I can possibly find any information either within the log files of CFT or the navigator to see why CFT had stopped?

The status of the CFT server can be viewed through two procedures, one is through the "cftping -v" command and the other through the CFT logs:

(1) When CFT server has been started, type the command "cftping -v" to check status of CFT. For eg:

/Axway/Synchrony_V4/TransferCFT_251/runtime/conf> cftstart

Starting CFT with IDPARM "IDPARM0" and 256 transferts active
CFT Working Directory : /Axway5/Synchrony_V4/TransferCFT_251/runtime
[=================================]100% RUNNING 39/26727

CFT started correctly.
CFTMAIN process id is 26727.
/Axway5/Synchrony_V4/TransferCFT_251/runtime/conf> cftping -v
cft is alive

Similarly when CFT is stopped the same command as mentioned above will give the status as below:

/Axway5/Synchrony_V4/TransferCFT_251/runtime/conf> cftstop
[=================================]100% STOPPED
CFT stopped correctly.
/Axway5/Synchrony_V4/TransferCFT_251/runtime/conf> cftping -v
cft: not running
   
(2) Also the status/ errors of CFT server are logged into the log files on path <CFT install directory>/log/  
    For e.g.:
     
/Axway5/Synchrony_V4/TransferCFT_251/runtime/log> ls -l
total 6
-rw-r--r--   1 indxfb02 indxfb         0 Nov  2 12:10 cftalog
-rw-r--r--   1 indxfb02 indxfb         0 Nov  2 12:11 cftlog
-rw-r--r--   1 indxfb02 indxfb      2936 Nov  2 12:11 cftlog_sav