When updating an Azure app service there was an unexpected error when swapping the slots over as part of the deployment. The deployment was run again and was successful but it lost the connection to its fixed public IP address. What would be the reason for this?
I looked at the VNET associated with the service and noticed that the "Outbound internet traffic" box wasn't ticked like other services I have deployed. I manually ticked it and applied the changes and the IP address was re-associated. Why would this have been undone by the failed deployment?
Thanks to Vinay's answer I was able to identify my issue
Make sure that both the production and staging slots have the same VNet and outbound settings.
In my case the staging slots were not in the VNET which may have been changed when the error occurred, leaving the app service with no outbound settings configured