Hi, @McTALAO. Welcome to the SmartThings Community!
I’m confused about the SmartThings Cloud Connector term you used since it’s different than a SmartApp (Connected Service).
The first integrates a device to the SmartThings platform through the Cloud and uses OAuth 2.0.
The second one is mostly used for automations with existing devices but it can also create new ones that would be cloud-managed but its type in the Developer Workspace is “Automation”.
So, please confirm which type of project you used because if the first (Device Integration > SmartThings Cloud Connector in the Developer Workspace), it doesn’t require a Confirmation URL.
Mmm this is weird, after you login, the discovery request should be issued to your cloud.
Could you check if the address you entered into the Developer Workspace passes the test of this SSL tester, please?
If it does, could you share the app ID of your project and the timestamp (including timezone) of your last attempt, please?
during testing I used two different Webhooks to try to investigate the problem,
the first on our main platform and the second on an another platform,
the results are Grade A and Grade B respectively.
For information, Keycloak, which implements the OAuth2 scheme, use self-signed certs;
could this be the problem?