We're trying to get our Exchange system up and running with SolidCP; Everything looks ok so far as I can tell, but...

When we try to create an exchange mailbox, we see the user created in AD successfully, however mailbox creations fails with the following error message.

Server was unable to process request. ---> Connecting to remote server <<redacted>> failed with the following error message : The WS-Management service does not support the request. For more information, see the about_Remote_Troubleshooting Help topic.
at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
at SolidCP.Providers.Exchange.ExchangeServer.CreateMailEnableUser(String upn, String organizationId, String organizationDistinguishedName, String securityGroup, String organizationDomain, ExchangeAccountType accountType, String mailboxDatabase, String offlineAddressBook, String addressBookPolicy, String accountName, Boolean enablePOP, Boolean enableIMAP, Boolean enableOWA, Boolean enableMAPI, Boolean enableActiveSync, Int64 issueWarningKB, Int64 prohibitSendKB, Int64 prohibitSendReceiveKB, Int32 keepDeletedItemsDays, Int32 maxRecipients, Int32 maxSendMessageSizeKB, Int32 maxReceiveMessageSizeKB, Boolean hideFromAddressBook, Boolean isConsumer, Boolean enabledLitigationHold, Int64 recoverabelItemsSpace, Int64 recoverabelItemsWarning)
at SolidCP.EnterpriseServer.ExchangeServerController.CreateMailbox(Int32 itemId, Int32 accountId, ExchangeAccountType accountType, String accountName, String displayName, String name, String domain, String password, Boolean sendSetupInstructions, String setupInstructionMailAddress, Int32 mailboxPlanId, Int32 archivedPlanId, String subscriberNumber, Boolean EnableArchiving)

In the SolidCP event logs, I see this:

ERROR: 'Hosted Microsoft Exchange Server 2016' ExtendToExchangeOrganization
System.Management.Automation.Remoting.PSRemotingTransportException: Connecting to remote server <<redacted>> failed with the following error message : The WS-Management service does not support the request. For more information, see the about_Remote_Troubleshooting Help topic.
at System.Management.Automation.Runspaces.AsyncResult.EndInvoke()
at System.Management.Automation.Runspaces.Internal.RunspacePoolInternal.EndOpen(IAsyncResult asyncResult)
at System.Management.Automation.RemoteRunspace.Open()
at SolidCP.Providers.HostedSolution.Exchange2016.OpenRunspaceEx()
at SolidCP.Providers.HostedSolution.Exchange2016.CreateMailEnableUserInternal(String upn, String organizationId, String organizationDistinguishedName, String securityGroup, String organizationDomain, ExchangeAccountType accountType, String mailboxDatabase, String offlineAddressBook, String addressBookPolicy, String accountName, Boolean enablePOP, Boolean enableIMAP, Boolean enableOWA, Boolean enableMAPI, Boolean enableActiveSync, Int64 issueWarningKB, Int64 prohibitSendKB, Int64 prohibitSendReceiveKB, Int32 keepDeletedItemsDays, Int32 maxRecipients, Int32 maxSendMessageSizeKB, Int32 maxReceiveMessageSizeKB, Boolean hideFromAddressBook, Boolean IsConsumer, Boolean enabledLitigationHold, Int64 recoverabelItemsSpace, Int64 recoverabelItemsWarning)
at SolidCP.Server.ExchangeServer.CreateMailEnableUser(String upn, String organizationId, String organizationDistinguishedName, String securityGroup, String organizationDomain, ExchangeAccountType accountType, String mailboxDatabase, String offlineAddressBook, String addressBookPolicy, String accountName, Boolean enablePOP, Boolean enableIMAP, Boolean enableOWA, Boolean enableMAPI, Boolean enableActiveSync, Int64 issueWarningKB, Int64 prohibitSendKB, Int64 prohibitSendReceiveKB, Int32 keepDeletedItemsDays, Int32 maxRecipients, Int32 maxSendMessageSizeKB, Int32 maxReceiveMessageSizeKB, Boolean hideFromAddressBook, Boolean isConsumer, Boolean enabledLitigationHold, Int64 recoverabelItemsSpace, Int64 recoverabelItemsWarning)

Any suggestions?