We have OES 2018 with two SLP DAs and serveral file servers that advertise their volumes to these DAs.
From time to time the service registrations are lost, only "rcslpd reload" on the file server brings them back.
I believe this is what's happening: when a SLP SA tries to refresh a service registration while the DA is temporarily not available (network interruption, server reboot, ...) then it removes the DA from its list of known DAs and never tries again.
Is this a bug or "works as designed"? To me this does not make sense.