Simplifying Matrix UI

Need suggestion on simplifying a Checkbox Grid UI (shown in below image left side) as it is not scale-able due to number items count (Varies from 100 - 240).

I had plans to go with the two column approach (right side of the image), but the only problem here is that user need to select the individual item to view its connections. As per user feedback, the UI needs to have better of ease of use to easily check their connections.

Let me know, whether there are any alternate solution.