1)Login to NetFlow Analyzer installed server->Go to Windows defender firewall->Inbound rules.
2)Now sort on Action tab to find out blocked rules->There should be blocked rules with criteria as "ANY" or "UDP" under protocol tab
and under Local Port and remote port there will be "ANY" criteria which is the reason why you are getting this message
3)Click
on the rule name->Protocols and ports->configure the port range
as below if your UDP listener port is 9996 by excluding UDP port alone.
0-9995,9997-65535
4)Save
the rule and repeat this for all blocked rules and then restart NetFlow
Analyzer service and check the issue and let us know.