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Sequoia Configuration - ASM Online Services Gateway


The ASM Online Services Gateway handles the communication of CDS messages between Sequoia and HMRC (direct, or via CSP's). This gateway can be found on the Sequoia Server machine and will be listed as 'ASM Sequoia Helios Gateway'.

For CCS-UK users this gateway will also handle all EDI messages once your Sequoia Server has been configured to send CDS declarations and CCS-UK have performed a table update on their system. This means that when you have been configured to send CDS declarations, any CDS / CHIEF and inventory messaging will be routed through ASM online services.


The gateway will connect to ASM Online Services over SSL via port 443. The gateway will establish and maintain a WebSocket connection to receive notifications when messages are available, and will otherwise make ad-hoc REST calls to to send and receive messages that are communicated by HMRC or from CSP's. Please ensure that your system administrator allows access to the internet for this service.


Configuration of this gateway is not necessary. The Sequoia user licence will provide any details that the gateway requires to create a secured connection to ASM Online Services.


The connection to ASM Online Services can be lost for various reasons. This can include planned downtime or in rare circumstances unplanned outages of ASM Online Services. Most typically, it will be your internet connection that has been interrupted by your service provider or your system administrator, or perhaps other networking issues. For these reasons, and maybe others that are not listed, the Sequoia Server may be unable to communicate with ASM Online Services.

Reconnecting Automatically

If you have a version of Sequoia Server installed which is v5.16 or greater, your Helios Gateway will automatically attempt to reconnect when a connection is lost.
If you have an earlier version of Sequoia, it will not automatically reconnect.

You should always ensure that you have upgraded your Sequoia Server to the latest available version.

Reconnecting Manually

You should only try to reconnect manually when:

  • The 'ASM Sequoia Helios Gateway' on the Sequoia Server fails to automatically reconnect.
  • You are not aware of any networking issues.
  • You are not aware of any internet connectivity problems.
  • There are no issues with ASM Online Services listed on the ASM Status page.

To reconnect, simply restart the 'ASM Sequoia Helios Gateway' on the Sequoia Server as follows:

  • Gain access to the Sequoia Server machine. If in doubt, contact your system administrator.
  • Open up the 'Services' window. If you don't know how to do this, you can find a guide online - a good example can be found by following this link.
  • Scroll down through the list of services until you find the service named 'ASM Sequoia Helios Gateway'.
  • Restart the service by right clicking on it and selecting 'Restart', or by clicking the appropriate toolbar button with the service selected.
  • If the gateway is able to establish communication, you will very shortly see updates to declarations / inventory records on your Sequoia client application.