2042565 - R2C Terminal XXXX in status DISC (SM21)

In SYSLOG report following infos :

DP Q0 4 Connection to user * (<XXX>), terminal 358 (<TERMINAL>) lost
DP Q0 4 Connection to user * (<XXX> ), terminal 414 (<TERMINAL ) lost
DP Q0 4 Connection to user * (<XXX>), terminal 468 (<TERMINAL>) lost
DIA 002 100 <XXX> <XXX> R2 C Terminal 00414 in status DISC

The corresponding developer trace file records (dev_w*):

M ***LOG R2C=> ThRqOutCheck, bad TM-state (00173DISC) [thxxhead.c 13179]
M in_ThErrHandle: 1
M *** ERROR => ThRqOutCheck: bad request (step 4, th_errno 4, action 1, level 1) [thxxhead.c 11535]
M {root-id=53C3E36883878350E10080000A00642D}_{conn-id=00000000000000000000000000000000}_0
M DpVmcGetVmByTmAdm: no VM found for T<NR>/M<NR> (locked VMs ignored)
M ThResetEmMagic: reset em magic for T<NR>/M<NR>

network, NIPING, NiIRead NiBufReceive (-6: NIECONN_BROKEN), Connection timed out , KBA , BC-CST-DP , Dispatcher, Task Handler , Problem