That’s a good clue!
I found this note in the Dante Controller manual:
External Word Clock: ‘No’ indicates that the device has been configured to use the internal clock source. ‘Yes’ indicates that the device has been configured to accept an external word clock source. NOTE: If the Dante device is configured to accept an external word clock source, it is important to make sure that the host equipment has been configured to provide its word clock to the Dante device. Check your product manual for more information.
When the Galaxy’s clock source is set to Internal, it does provide that clock to the Dante network, correct? If not, you may need to use an alternative clocking method.
Your ethernet cable isn’t longer than 100 meters, right?