User going offline that are sitting idle

Hello,

Having an issue where a couple of users going offline. Not sure if sitting idle has anything to do with it but the other users are extremely active. The two users in question keep going offline and I’m getting this warning every couple of seconds since this started happening:

org.jivesoftware.openfire.nio.OfflinePacketDeliverer - Could not route packet

The server is only utilizing 10% of memory and 9% cpu. Openfire 7.1% java memory used. Client connections is set to “Do not disconnect”

Ubuntu v18.04
Openfire v4.5.3
Strophe v2

Any ideas?