TLS Certificate issue with Fenix 7 and Epix (Gen 2)

Runcasts users who recently upgraded to the Fenix 7 or Epix Gen 2 are reporting that their connections are suddenly not working correctly. It's returning and error code '0' which comes from Communications.makeWebRequest and maps to UNKNOWN_ERROR.

I know from past experience that this can often be caused my TLS issues so have built a tool to verify this available here: https://apps.garmin.com/en-US/apps/1f8aecd2-d37f-49ec-bcdd-f19feb9e8994 (the source code is also available to inspect, linked from the store page).

It appears that Runcasts Sectigo certificate is not being accepted by the Fenix 7 or Epix 7, while as far as I can tell, it's accepted by other devices in the fleet, including the Fenix 6.

I'll include (2) pics, one of a Fenix 6 where all the tests are green and one from a Fenix 7 where the Sectigo certificate fails.

For context, I originally used Let's Encrypt, but that had similar issues of not working on some device + firmware combinations, so I went with a more standard certificiate, Sectigo, which has worked well. This is the first time I'm hearing reports of this particular cert not working.

The request would be to update the certificate store on the watch so that this certificate works.

As a note, when testing this, make sure you're connecting through WI-Fi and not Bluetooth to the phone. This can be a confounding factor, if it connects using the phone, then presumably it uses the cert store on the phone which is often up-to-date / complete. However, with Wi-Fi, it uses the whatever's on the watch, and that, in general, has been more limited.