Building Citrix Enviroments in Microsoft Azure is pretty easy these days, now there are some issues with using the latest features especially with EDT. If you are encountering issues with running Citrix in Azure and with EDT and when you try to connect to the enviroment you might get this error message “Connection Interrupted” or getting issues with random grey screens when starting either with the Workspace app or Citrix Receiver.
This issue occurs because of MTU/IP fragmentation issues on the Citrix NetScaler Gateway. Based upon my research so far, UDP Fragmentation is not something that the NetScaler Gateway doesn’t handle for EDT. So when the Workspace App or Citrix Receiver tries to establish a connection on UDP the NetScaler will drop the traffic because it is expenting a MTU of 1350 and not 1500. That’s why we need to change the output buffers on the default.ica to 1350 to not cause MTU fragmentation to happen on the NetScaler Gateway.
Open the default.ica file for editing (by default it is located in C:\inetpub\wwwroot\Citrix\<StoreName>\App_Data\default.ica)
Add the following options under the [Application] section:
OutBufLength=1400
udtMSS=1400 (add this line if using Receiver for Windows 4.7 – 4.12, Receiver for Mac 12.5 – 12.9, Receiver for Linux 13.6 – 13.10, Receiver for iOS 7.2 – 7.5.x, Receiver for Android 3.12.3 – 3.13.x, or Workspace app 1808 for Mac, Linux, iOS, or Android)
edtMSS=1400 (add this line if using Workspace app for Windows 1808+)
So when you connect the ICA file shoud look like this.
NOTE: This is also currently part of the Known issues for the latest version as well, so you can keep track of it here –> https://docs.citrix.com/en-us/citrix-virtual-apps-desktops/whats-new/known-issues.html
Now once this is changed, the connection will work and you will be able to connect using EDT.