Debugging
View SourceTLS client errors
If you see the following in your logs:
14:26:06.926 [info] ['TLS', 32, 'client', 58, 32, 73, 110, 32, 115, 116, 97, 116, 101, 32, 'cipher', 32, 'received SERVER ALERT: Fatal - Unknown CA', 10]
This probably indicates that the signing certificate hasn't been uploaded to NervesHub so the device can't be authenticated. Double check that you ran:
mix nerves_hub.ca_certificate register my-signer.cert
Another possibility is that the device wasn't provisioned with the certificate that's on NervesHub.
See also NervesHubWeb: Potential SSL Issues