EX4100 Can't see in my Cloud, but can reach via network share

My Cloud OS 5 Personal & Network Attached Storage My Cloud EX Series
15

You don’t need to access the web interface for a soft reset. Have a look at How to Reset a My Cloud EX4100 Device | by rahmanarif | Medium but do some research and googling first to make sure it doesn’t wipe out your user data.
I would suggest trying the 4 second reset first to see if it’s fixed. If not try the 40 second reset.