NRPE checks failing

Hi there,

recently i observe a strange behavior regarding nrpe-checks on only a few hosts.

I.E. on the same host there are multiple nrpe checks running, all except of one work perfectly but the last returns: “CHECK_NRPE: Received 0 bytes from daemon. Check the remote server logs for error messages.” (as displayed in icinga2web) or “CHECK_NRPE: Socket timeout after 10 seconds.” (if check is run manually on icinga2 server)
Other times the check works as intended.

They’re windows hosts with nsclient++ running, nsclient.ini is a company wide default and the same checks work on other hosts perfectly.

What I checked so far:
Ports are open on all clients (5666)
increasing the timeout param does not affect the outcome
network-delay shouldn’t be a thing, because they’re within the same datacenter

nsclient.ini is set up:

 allowed hosts = ip-icinga-server
 ssl options = no-sslv2,no-sslv3
 verify mode = none
 insecure = true
 allow arguments = true
 allow nasty characters=true

nsclient.log contains two different errors:
error:D:\source\nscp\service\NSClient++.cpp:906: Failed to execute command
error:D:\source\nscp\include\socket/connection.hpp:149: Failed to send data: The file handle supplied is not valid

I’m glad about any hint that may lead to a solution for this issue.

Kind regards,