What causes 403 Forbidden response from event server?

We’re seeing intermittent 403 responses from an event server using the attached syntax. This alarm failed in our application, but when it was resent we got 200 OK in response. According to your documentation, 403 Forbidden corresponds to an API error. What could be causing this within the API?

<?xml version="1.0" encoding="utf-8"?> <AnalyticsEvent xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:milestone-systems"> <EventHeader><ID>00000000-0000-0000-0000-000000000000</ID> <Timestamp>2021-11-01T18:21:07-04:00</Timestamp><Type>[object_name]</Type><Message>[alarm_name]</Message> <Source><FQID><ServerId><Id>[server_id]</Id></ServerId><ObjectId>[object_id]</ObjectId></FQID></Source> </EventHeader><ObjectList><Object><BoundingBox><Top>0.2569</Top><Left>0.2583</Left><Bottom>0.4861</Bottom><Right>0.3167</Right></BoundingBox></Object></ObjectList></AnalyticsEvent>

Can you please confirm that url and request data are same in first and second request? Can you provide url and request object.