Can you try to capture logs from the device while you’re trying to access the web page? See this post for how to stream logs wirelessly.
Interesting that you’re using HA and C4! Theoretically it should work, but I wonder if the C4 driver is putting a load on the web server that’s causing it to crash. Logs should be helpful to diagnose that.
The Garage Door Obstruction sensor uses the garage opener’s electric beam across the garage opening to report its state. It would change to the problem state when a vehicle or object is blocking that beam.