The Yodeck Player (based on Raspberry Pi) automatically detects on start-up the "preferred" resolution of the connected monitor (usually, its native resolution). In some cases, the preferred resolution is not detected properly:
Powering up your Player without a screen connected.
Powering up your Player and screen at the same time (e.g. after a power failure). If your screen is slow on startup, it does not report its resolutions in time to the Player.
In this case, the standard VGA resolution of 640x480 or 1024x768 is used. Rebooting your Player will resolve this issue (temporarily).
If you are having constant issues like this, then you have two options for a permanent solution:
Set the resolution of the Player to a standard one. Your Player will always use this resolution, regardless if you have attached a screen or not, or if the attached screen supports it or not.
Increase the time the Player waits for detecting the screen. This delay is set by default to 3 seconds. You can increase it, to allow your screen to properly start and allow the Player to detect it.
To do this:
Go to your Monitor entry in the Yodeck Portal,
Go to the "Advanced" tab, and then click the "Customization" tab
Make sure the "Allow Raspberry config.txt Override" toggle is set to "ON",
Add the following line to the "Raspberry config.txt Override Directives", using the number of seconds that works for you: bootcode_delay=8
Make sure you click the "Save" button, so that the configuration you did is saved.
Reach out if you are still having problems!