White dots, lines, or distortion means your TV is not getting a stable signal.
If you are using an OSSC, set your OSSC to output 480p (Line 2x mode). The HDMI timing of the OSSC in Line 3x, 4x, and 5x is not standard.
To make the signal stable, you can try:
1. Checking the included HDMI extender to make sure that it is working properly by trying another one or connecting the mClassic to your HDMI without it. You may have to temporarily use another source if clearance is an issue. You can also use any HDMI 2.0 or higher HDMI switch or splitter to fit the mClassic.
2. Check the regular HDMI cable from the female side of the mClassic to your TV by trying a different HDMI cable rated 2.0 or higher.
3. Check the USB power source of the mClassic by trying different USB power ports and a different Micro USB cable.
If the problem persists after trying these steps, please submit a support ticket.