Failed to write to socket 9; Unable to start save session with nsrmmd AIX 7.1 Networker 19.3

Hi, while starting up a backup, frequently see errors:

      Failed to write to socket 9; Unable to start save session with nsrmmd      (see a full log below)

The backup is failing for that saveset and finished with error: save: backup of save set is unsuccessful.

Usually restart for that exactly saveset runs well with no issues while occasionally it may require another restart to proceed without "Failed to write to socket" error. The thing is that, there are numerous savesets in a backup and such issue may affect any saveset in arbitrary order. In most cases I don't see such error but it is unpredictable when error may pops up next time and backup needs be restarted.

The server in question "192.168.46.146" is NW mgmt server and looks like port 8639 becomes unavailable (temporarily) or is too busy to respond while I can't see anything bad with "192.168.46.146" in general - there are numerous backups running on that server with no visible issues.

"192.168.46.146" runs Networker/LGTO ver. 19.3.0.2 and client tested with versions 9.2.1.1, 18.0, 18.1, 19.2, 19.3.x.x with the same exact results.

Does anyone saw the same error or may recommend anything? Verified to be the same while using a workflow and "save" command from client.

Thanks!

 ===========================================================

Provided below is a log for a specific saveset when problem has been encountered - it is the same for other savesets (if/when happens).

  ------------------------------------

/disks/nasbld/nas55/nw/9.2.1/rpc/lib/c_tcp.c:1386 Failed to write to socket 9; peer = 192.168.46.146:[8639], errno = There is no process to read data written to a pipe.

Unable to start save session with nsrmmd on vlp-filenw02.dhebak: RPC send operation failed; peer = 192.168.46.146:8639, errno = There is no process to read data written to a pipe.

mmsave setup failed: RPC send operation failed; peer = 192.168.46.146:8639, errno = There is no process to read data written to a pipe.

Unable to set up the direct save with server 'vlp-filenw02.dhebak': RPC send operation failed; peer = 192.168.46.146:8639, errno = There is no process to read data written to a pipe..

The connection to the NetWorker server or storage node was lost before the save operation completed: There is no process to read data written to a pipe.

get_mbs_version() (tid:43348941709770761): ERRORDo MBS: cannot get emitter 0 version.

DPSS save point 'lpa-nwstgfe1.dhe.duke.edu:/epic/prd08' has encountered a critical error.