APNs Certificate Test: CAPNWorkerThread:GetAPNSocket Failed

Hello again,

I know, I have a lot of question, but I hope someone can help.

I've installed the APNs Certificate and clicked "Test Now", but I always get that the test Failed with the Error "CAPNWorkerThread:GetAPNSocket".
The ports 2195 & 2196 are opened at our firewall. The Log Files of iOS MDM Sync Log says:

- Failed to get socket
- Failure to connect to APNS. Error code: -2146893052 Error Message: TLS Data Error

There are no deny errors on our firewall.

Any Ideas ?

Regards,
D. Oeden