I was having similar issues. I finally narrowed it down to static discharge.
Saw Dust generates huge amounts of static. The dewalt router is ungrounded so when there is a discharge it wants to take the easiest path. Sound like that path is through your controller.
I have added a ground plug and wire to my dewalt and grounded the router. I have also run a bare cooper wire through the inside of my dust collection hose and grounded one end to the dust collector and the other to the dewalt.
Since doing this I have had zero disconnects.