The 192.168… that is your internal network’s IP address. That IP is assigned by your network router at home. The non-static IP that your ISP assigns you is your external IP. The world outside your home (the Internet) only sees your external IP - and if you were to connect from outside your home that’s the IP you would use. They don’t see your internal IP (192.168…) - the internal IPs are only visible to devices within your home network and those devices like say the My Cloud and your computer (when you are at home) talk to each other using the internal network IP addresses.
It’s kind of confusing, to me at least, what your exact issue is without a more detailed description from you. Just want to say, your internal IP should usually stay same when accessing from your internal network if you don’t shut down the My Cloud device. Once you shut it down, the next time it reboots, it may or may not be assigned a different IP by your router. If your main issue is that the 192.168… address that you use to access the dashboard keeps changing every now and then - then that is because your router assigns the device a new internal IP everytime you rebooted either your router or your My Cloud…and to stop that from happening you need to assign a static IP on your router for your My Cloud.
To assign a static IP - google to lookup the manual for your specific model of router and then look in it to see how to do that. But I am not sure if that is what you are really trying to solve…as I am not sure if you are talking about URL when accessing from outside the network (outside home) or inside the network (within home)…because it could mean you are either talking about external IP (assigned by ISP) or the internal IP (assigned by your router).