failed to download file: http request failed: GET dial tcp x.x.x.x:443 i/o timeout

I am deploying the Custom Script Extension to a VMSS running Ubuntu 18.04. I configured the custom script extension with the CommandToExecute in public settings; fileURIs, storage creds in protected settings using the az vmss extension set command. The fileURI points to shell script on blob storage account in the same VNet as the VMSS.

I see that the extension is registered with the VMSS. However, the extension fails to enable. Looking at /var/log/azure/custom-script/handler.log, i see the error **"http request failed: Get [REDACTED] dial tcp x.x.x.x:443 i/o timeout"**

I verified that a curl to the blob uri works without issues, it seems the Go script is unable to download the blob uri though. I tried replacing blob uri with a public github url without success.