Error after move behind Juniper SRX 300 Firewall

[Tal_Baron]

Hi,
We are running 2 windows machines - 1 web/application server and 1 SQL DB server.
After a move of the Web server behind at the Juniper firewall (DB was not moved) NServieBus fails to connect from Web to DB servers ALTHOUGH all bi-directional traffic on all ports were open on firewall. Main error flagging up is MSDTC fails to connect.

Error appears - System.Transactions.TransactionManagerCommunicationException: Communication with the underlying transaction manager has failed. ---> System.Runtime.InteropServices.COMException: The MSDTC transaction manager was unable to push the transaction to the destination transaction manager due to communication problems. Possible causes are: a firewall is present and it doesn't have an exception for the MSDTC process, the two machines cannot find each other by their NetBIOS names, or the support for network transactions is not enabled for one of the two transaction managers. (Exception from HRESULT: 0x8004D02A)

AND

Source:        NServiceBus.Hosting.Windows.WindowsHost, NServiceBus.Host, Version=4.7.0.0, Culture=neutral, PublicKeyToken=9fc386479f8a226c
Date:          20/02/2019 11:03:59
Event ID:      0
Task Category: None
Level:         Information
Keywords:      Classic
User:          N/A
Computer:      p5552684
Description:
2019-02-20 11:03:59,678 [13] INFO  NServiceBus.Unicast.Transport.TransportReceiver [(null)] - Failed to process message
System.Data.ProviderIncompatibleException: An error occurred while getting provider information from the database. This can be caused by Entity Framework using an incorrect connection string. Check the inner exceptions for details and ensure that the connection string is correct. ---> System.Data.ProviderIncompatibleException: The provider did not return a ProviderManifestToken string. ---> System.Transactions.TransactionException: The operation is not valid for the state of the transaction.
   at System.Transactions.TransactionState.EnlistPromotableSinglePhase(InternalTransaction tx, IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Transaction atomicTransaction, Guid promoterType)
   at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Guid promoterType)
   at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification)
   at System.Data.SqlClient.SqlInternalConnection.EnlistNonNull(Transaction tx)
   at System.Data.SqlClient.SqlInternalConnection.Enlist(Transaction tx)
   at System.Data.ProviderBase.DbConnectionInternal.ActivateConnection(Transaction transaction)
   at System.Data.ProviderBase.DbConnectionPool.PrepareConnection(DbConnection owningObject, DbConnectionInternal obj, Transaction transaction)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at System.Data.SqlClient.SqlProviderServices.UsingConnection(SqlConnection sqlConnection, Action`1 act)
   at System.Data.SqlClient.SqlProviderServices.UsingMasterConnection(SqlConnection sqlConnection, Action`1 act)
   at System.Data.SqlClient.SqlProviderServices.GetDbProviderManifestToken(DbConnection connection)
   at System.Data.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
   --- End of inner exception stack trace ---
   at System.Data.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
   at System.Data.Entity.ModelConfiguration.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection)
   --- End of inner exception stack trace ---
   at System.Data.Entity.ModelConfiguration.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection)
   at System.Data.Entity.ModelConfiguration.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest& providerManifest)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.InternalContext.ForceOSpaceLoadingForKnownEntityTypes()
   at System.Data.Entity.DbContext.System.Data.Entity.Infrastructure.IObjectContextAdapter.get_ObjectContext()
   at TripleJumpTech.RevenueAssurance.Core.EventManagement.Domain.ManagmentDomainModel..ctor() in d:\Daniel\Work\TripleJump\RMS\RMS\dev\src\core\TripleJumpTech.RevenueAssurance.Core\EventManagement\Domain\ManagmentDomainModel.cs:line 91
   at TripleJumpTech.RevenueAssurance.SalesServer.MessageHandlers.CheckRefreshIntegrationsCommandhandler.Handle(CheckRefreshRTSSuiteDataCommand message) in d:\Daniel\Work\TripleJump\RMS\RMS\dev\src\core\TripleJumpTech.RevenueAssurance.SalesServer\MessageHandlers\CheckRefreshIntegrationsCommandhandler.cs:line 155
   at NServiceBus.Unicast.HandlerInvocationCache.Invoke(Object handler, Object message, Dictionary`2 dictionary) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\HandlerInvocationCache.cs:line 61
   at NServiceBus.Unicast.Behaviors.LoadHandlersBehavior.<Invoke>b__1(Object handlerInstance, Object message) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\LoadHandlersBehavior.cs:line 42
   at NServiceBus.Unicast.Behaviors.InvokeHandlersBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\InvokeHandlersBehavior.cs:line 27
   at NServiceBus.Sagas.SagaPersistenceBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Sagas\SagaPersistenceBehavior.cs:line 31
   at NServiceBus.Sagas.AuditInvokedSagaBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Sagas\AuditInvokedSagaBehavior.cs:line 14
   at NServiceBus.Unicast.Behaviors.SetCurrentMessageBeingHandledBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\SetCurrentMessageBeingHandledBehavior.cs:line 21
   at NServiceBus.Pipeline.PipelineExecutor.Execute[T](BehaviorChain`1 pipelineAction, T context) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Pipeline\PipelineExecutor.cs:line 138
   at NServiceBus.Pipeline.PipelineExecutor.InvokeHandlerPipeline(MessageHandler handler) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Pipeline\PipelineExecutor.cs:line 67
   at NServiceBus.Unicast.Behaviors.LoadHandlersBehavior.Invoke(ReceiveLogicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\LoadHandlersBehavior.cs:line 39
   at NServiceBus.DataBus.DataBusReceiveBehavior.Invoke(ReceiveLogicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\DataBus\DataBusReceiveBehavior.cs:line 69
   at NServiceBus.Pipeline.PipelineExecutor.Execute[T](BehaviorChain`1 pipelineAction, T context) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Pipeline\PipelineExecutor.cs:line 138
   at NServiceBus.Unicast.Messages.ExecuteLogicalMessagesBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Messages\ExecuteLogicalMessagesBehavior.cs:line 28
   at NServiceBus.UnitOfWork.UnitOfWorkBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\UnitOfWork\UnitOfWorkBehavior.cs:line 44
   at NServiceBus.Unicast.Behaviors.ForwardBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\ForwardBehavior.cs:line 24
   at NServiceBus.Audit.AuditBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Audit\AuditBehavior.cs:line 17
   at NServiceBus.Unicast.Behaviors.ImpersonateSenderBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\ImpersonateSenderBehavior.cs:line 37
   at NServiceBus.Unicast.Behaviors.MessageHandlingLoggingBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\MessageHandlingLoggingBehavior.cs:line 23
   at NServiceBus.Unicast.Behaviors.ChildContainerBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\ChildContainerBehavior.cs:line 17
   at NServiceBus.Unicast.Transport.TransportReceiver.OnTransportMessageReceived(TransportMessage msg) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Transport\TransportReceiver.cs:line 431
   at NServiceBus.Unicast.Transport.TransportReceiver.ProcessMessage(TransportMessage message) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Transport\TransportReceiver.cs:line 362
   at NServiceBus.Unicast.Transport.TransportReceiver.TryProcess(TransportMessage message) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Transport\TransportReceiver.cs:line 259
   at NServiceBus.Transports.Msmq.MsmqDequeueStrategy.Action() in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Transports\Msmq\MsmqDequeueStrategy.cs:line 236

Event Xml:

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="NServiceBus.Hosting.Windows.WindowsHost, NServiceBus.Host, Version=4.7.0.0, Culture=neutral, PublicKeyToken=9fc386479f8a226c" />
    <EventID Qualifiers="0">0</EventID>
    <Level>4</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2019-02-20T11:03:59.725088200Z" />
    <EventRecordID>110175</EventRecordID>
    <Channel>Application</Channel>
    <Computer>p5552684</Computer>
    <Security />
  </System>
  <EventData>
    <Data>2019-02-20 11:03:59,678 [13] INFO  NServiceBus.Unicast.Transport.TransportReceiver [(null)] - Failed to process message
System.Data.ProviderIncompatibleException: An error occurred while getting provider information from the database. This can be caused by Entity Framework using an incorrect connection string. Check the inner exceptions for details and ensure that the connection string is correct. ---&gt; System.Data.ProviderIncompatibleException: The provider did not return a ProviderManifestToken string. ---&gt; System.Transactions.TransactionException: The operation is not valid for the state of the transaction.
   at System.Transactions.TransactionState.EnlistPromotableSinglePhase(InternalTransaction tx, IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Transaction atomicTransaction, Guid promoterType)
   at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Guid promoterType)
   at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification)
   at System.Data.SqlClient.SqlInternalConnection.EnlistNonNull(Transaction tx)
   at System.Data.SqlClient.SqlInternalConnection.Enlist(Transaction tx)
   at System.Data.ProviderBase.DbConnectionInternal.ActivateConnection(Transaction transaction)
   at System.Data.ProviderBase.DbConnectionPool.PrepareConnection(DbConnection owningObject, DbConnectionInternal obj, Transaction transaction)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal&amp; connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal&amp; connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal&amp; connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at System.Data.SqlClient.SqlProviderServices.UsingConnection(SqlConnection sqlConnection, Action`1 act)
   at System.Data.SqlClient.SqlProviderServices.UsingMasterConnection(SqlConnection sqlConnection, Action`1 act)
   at System.Data.SqlClient.SqlProviderServices.GetDbProviderManifestToken(DbConnection connection)
   at System.Data.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
   --- End of inner exception stack trace ---
   at System.Data.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
   at System.Data.Entity.ModelConfiguration.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection)
   --- End of inner exception stack trace ---
   at System.Data.Entity.ModelConfiguration.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection)
   at System.Data.Entity.ModelConfiguration.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest&amp; providerManifest)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.InternalContext.ForceOSpaceLoadingForKnownEntityTypes()
   at System.Data.Entity.DbContext.System.Data.Entity.Infrastructure.IObjectContextAdapter.get_ObjectContext()
   at TripleJumpTech.RevenueAssurance.Core.EventManagement.Domain.ManagmentDomainModel..ctor() in d:\Daniel\Work\TripleJump\RMS\RMS\dev\src\core\TripleJumpTech.RevenueAssurance.Core\EventManagement\Domain\ManagmentDomainModel.cs:line 91
   at TripleJumpTech.RevenueAssurance.SalesServer.MessageHandlers.CheckRefreshIntegrationsCommandhandler.Handle(CheckRefreshRTSSuiteDataCommand message) in d:\Daniel\Work\TripleJump\RMS\RMS\dev\src\core\TripleJumpTech.RevenueAssurance.SalesServer\MessageHandlers\CheckRefreshIntegrationsCommandhandler.cs:line 155
   at NServiceBus.Unicast.HandlerInvocationCache.Invoke(Object handler, Object message, Dictionary`2 dictionary) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\HandlerInvocationCache.cs:line 61
   at NServiceBus.Unicast.Behaviors.LoadHandlersBehavior.&lt;Invoke&gt;b__1(Object handlerInstance, Object message) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\LoadHandlersBehavior.cs:line 42
   at NServiceBus.Unicast.Behaviors.InvokeHandlersBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\InvokeHandlersBehavior.cs:line 27
   at NServiceBus.Sagas.SagaPersistenceBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Sagas\SagaPersistenceBehavior.cs:line 31
   at NServiceBus.Sagas.AuditInvokedSagaBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Sagas\AuditInvokedSagaBehavior.cs:line 14
   at NServiceBus.Unicast.Behaviors.SetCurrentMessageBeingHandledBehavior.Invoke(HandlerInvocationContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\SetCurrentMessageBeingHandledBehavior.cs:line 21
   at NServiceBus.Pipeline.PipelineExecutor.Execute[T](BehaviorChain`1 pipelineAction, T context) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Pipeline\PipelineExecutor.cs:line 138
   at NServiceBus.Pipeline.PipelineExecutor.InvokeHandlerPipeline(MessageHandler handler) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Pipeline\PipelineExecutor.cs:line 67
   at NServiceBus.Unicast.Behaviors.LoadHandlersBehavior.Invoke(ReceiveLogicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\LoadHandlersBehavior.cs:line 39
   at NServiceBus.DataBus.DataBusReceiveBehavior.Invoke(ReceiveLogicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\DataBus\DataBusReceiveBehavior.cs:line 69
   at NServiceBus.Pipeline.PipelineExecutor.Execute[T](BehaviorChain`1 pipelineAction, T context) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Pipeline\PipelineExecutor.cs:line 138
   at NServiceBus.Unicast.Messages.ExecuteLogicalMessagesBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Messages\ExecuteLogicalMessagesBehavior.cs:line 28
   at NServiceBus.UnitOfWork.UnitOfWorkBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\UnitOfWork\UnitOfWorkBehavior.cs:line 44
   at NServiceBus.Unicast.Behaviors.ForwardBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\ForwardBehavior.cs:line 24
   at NServiceBus.Audit.AuditBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Audit\AuditBehavior.cs:line 17
   at NServiceBus.Unicast.Behaviors.ImpersonateSenderBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\ImpersonateSenderBehavior.cs:line 37
   at NServiceBus.Unicast.Behaviors.MessageHandlingLoggingBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\MessageHandlingLoggingBehavior.cs:line 23
   at NServiceBus.Unicast.Behaviors.ChildContainerBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Behaviors\ChildContainerBehavior.cs:line 17
   at NServiceBus.Unicast.Transport.TransportReceiver.OnTransportMessageReceived(TransportMessage msg) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Transport\TransportReceiver.cs:line 431
   at NServiceBus.Unicast.Transport.TransportReceiver.ProcessMessage(TransportMessage message) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Transport\TransportReceiver.cs:line 362
   at NServiceBus.Unicast.Transport.TransportReceiver.TryProcess(TransportMessage message) in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Unicast\Transport\TransportReceiver.cs:line 259
   at NServiceBus.Transports.Msmq.MsmqDequeueStrategy.Action() in c:\BuildAgent\work\1b05a2fea6e4cd32\src\NServiceBus.Core\Transports\Msmq\MsmqDequeueStrategy.cs:line 236
</Data>
  </EventData>
</Event>

Any suggestions?
Would placing the DB server as well behind the firewall help?

[ramonsmits]

@Tal_Baron

all bi-directional traffic on all ports were open on firewall. Main error flagging up is MSDTC fails to connect.

What do you mean with that? There is a firewall and you seem to be using MSDTC so you need to open up all MSDTC related ports too.

See the following SO post for help:

• MSDTC and firewall - Stack Overflow

You are doing something with Entity Framework which is used in a NServiceBus handler which in turn wants to connect to a database. This is not a direct NServiceBus issue

You could move the servers to all be in the same network segment to resolve the MSDTC connectivity issue.

Alternatively, you could see if you can remove the dependency on MSDTC. Based on the stacktrace it seems you are using MSMQ. Maybe consider enabling the Outbox feature and use Entify Framework integration:

• Outbox • NServiceBus • Particular Docs
• Entity Framework integration with SQL Persistence • Sql Persistence Samples • Particular Docs

But removing the dependency on MSDTC probably is a bridge too far as that requires your business logic to not rely on distributed transactions.