Do you have the mobile App loaded on your smartphone? That is one way to get into your Unleashed GUI. The other way is to scan your network to get the IP address of your R510s.
In either Apple Mac or Windows 10 you can use the following command at the command prompt:
This will produce a list of all of the devices on my home's network and their corresponding MAC addresses. Just run down the list with your Mac or Windows browser substituting the IP addresses that you found with the "arp -a" command and you will get the Unleashed login screen when you hit the proper IP address.