Mobile Coach App cannot connect with deepstream

Today our clients cannot connect to the MC-backend anymore.
When the app starts metro logs following error message:

Furthermore the backend cannot connect to the deepstream-service:

We were sending some media files from the backend to the clients, when the MC WebDesigner freezed and the clients lost the connection.
After this we tried to reboot the server and the containers. This didn’t resolved sadly the problem.
Since the SSL-certificates are due in 3 days, we tought maybe there are some certifacte problem.
So we renewed them with no effect on our problem.

Hope I gave enough informations and I’m looking forward to any help :).