Hi All, I am having random users periodically losing connection to the exchange server. I am seeing a lot of Source: MSExchange Availability Event Event ID: 4002 This is a detailed description of the event. can anyone shed any light?

Process 2416: ProxyWebRequest CrossSite from S-1-1-0 to https://**mail02.***.nche.edu/EWS/Exchange.asmx failed. Caller SIDs: NetworkCredentials. The exception returned is Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequestProcessingException: System.Web.Services.Protocols.SoapException: The authenticated user doesn't have sufficient privileges to issue this request.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.Proxy.Service.EndGetUserAvailability(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.FreeBusyApplication.EndProxyWebRequest(ProxyWebRequest proxyWebRequest, QueryList queryList, Service service, IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequest.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.AsyncWebRequest.EndInvokeWithErrorHandling(). The request information is ProxyWebRequest type = CrossSite, url = https://***mail02.***.nche.edu/EWS/Exchange.asmx
Mailbox list = <*****, Peter>SMTP:P*****@A***NET.EDU, Parameters: windowStart = 5/1/2015 12:00:00 AM, windowEnd = 7/1/2015 12:00:00 AM, MergedFBInterval = 30, RequestedView = FreeBusy
. ---> System.Web.Services.Protocols.SoapException: The authenticated user doesn't have sufficient privileges to issue this request.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.Proxy.Service.EndGetUserAvailability(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.FreeBusyApplication.EndProxyWebRequest(ProxyWebRequest proxyWebRequest, QueryList queryList, Service service, IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequest.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.AsyncWebRequest.EndInvokeWithErrorHandling()
   --- End of inner exception stack trace ---
. Name of the server where exception originated: ***MAIL01. Make sure that the Active Directory site/forest that contain the user's mailbox has at least one local Exchange 2010 server running the Availability service. Turn up logging for the Availability service and test basic network connectivity.

Could this be related to my issues? Any suggestions?

Thank You

• Edited by nickels_1050 3 hours 8 minutes ago