Hello Danilo,
Thank you for bringing this up. There are some factors to consider when this issue occurred like compatible monitor, adapter used, etc. Let's sort this out. However, to be able to understand the issue better, can you give us more details by answering these following questions:
• Can you tell us the make and model of the external monitor?
• Have you tried using other similar adapter to see if there are any changes?
• Can you tell us if the flickering/disconnection responds to an app/program? Were you able to check the screen resolution as well?
• What troubleshooting steps have you tried so far?
• Can you confirm if the device has the latest firmware update installed? How about the graphics driver?
Let us know so we can help you further.