If the serial data is being corrupted, you could try looping the cable between the DM and the host computer several times around a large high permeability ferrite toroid.
The material is important. Most toroids you will come across are more likely to be powdered iron, which is usually coated with a coloured coating. Powdered iron will not work in this application. Inverter grade ferrite may work, but is less than ideal bit will be better than nothing.
If this idea looks promising in solves the noise problem, we can try and source the right stuff
Ferrite will always be a dull grey/black in appearance as in the picture below. If its yellow, or red or brown or some other colour its definitely not ferrite. The light has reflected brightly off ferrite in the picture below, it looks almost silver, but it should look more a dull dark almost mat black in more normal light.
This will be far more effective than the usual clamp around type of ferrite sleeve you will see everywhere.
Nobody uses the toroid method because its big and ugly. The hole obviously needs to be large enough for the connector to pass through, and the wire cannot be wound around neatly. But its much more effective.