Hi,

Is the Runtime actually active on the Unified PC? Please check the SIMATIC Runtime Manager and if not, activate it.

It would also be advisable to run the WinCC Unified Configuration tool again to check the access type (IP or name) among other things.

The following FAQ also tells you several points to check in order to establish a connection to the Unified PC RT:

Settings for communication with WinCC Unified Runtime on the runtime device