While running cmdlet "Export-LogReportCsv" and setting parameter "StartDateRange" before two weeks (or more), 
"The remote server returned an unexpected response: (502) Bad Gateway" error may show as below.

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> Export-LogReportCsv -OutputFile "C:\temp\CitrixConfigLog.csv" -StartDateRange "20XX-XX-21 09:00"

Export-LogReportCsv : The remote server returned an unexpected response: (502) Bad Gateway.
    + CategoryInfo          : NotSpecified: (:) [Export-LogReportCsv], ProtocolException
    + FullyQualifiedErrorId : Citrix.XDPowerShell.Status.CommunicationError,Citrix.ConfigurationLogging.Sdk.Commands.ExportLogReportCsvCommand
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And if setting the "StartDateRange" to a nearby DateTime, the issue can be resolved.

Please set the "StartDateRange" to a nearby DateTime.

Problem Cause

This is Product Limitation.
When the "StartDateRange" is set before two weeks (or more), executing cmdlet "Export-LogReportCsv" will cause a high site DB load and the query will take too long. As a result, this issue may happen.