Adaptive transport is a new data transport mechanism for XenApp and XenDesktop and available in Citrix policies. When set to Preferred, it uses data transport over EDT as primary and fallback to TCP.

By default, it uses TCP and adaptive transport is disabled.

However, for testing purposes, we can set Diagnostic mode to only use EDT and disable the fallback.

We can fix this issue using the following steps:

1. Initially, we will test with the policy set to Preferred.  [No UDP Ports will be open]

We can do this using the following steps:

• Firstly, launch the Desktop.
• Then from the command prompt browse to “C:\Program Files (x86)\Citrix\System32“
• Finally, we have to run ‘CtxSession’

We will see that it uses TCP with CGP and Session Reliability encapsulates the ICA protocol.

2. Now, we have to run CtxSession /v for verbose output. Here we can see that VDA is using port 2598.

3. Next, we will set the policy to ‘Diagnostic mode’.

We must ensure that UDP 1494 and 2598 ports open on the VDA. Now we can run CtxSession /v to get confirmation that we are using UDP 2598.

This means that HDX Enlightened Data Transport is being used with Session Reliability. We can also check Director and see that whether the protocol will be set as UDP.

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