Unfortunately many boxes use the "M8S" branding, so it's hard to know for sure what you're dealing with.
The authentication problem though, assuming you've tried the basic reboot...... I'd suggest assigning a static IP, confirming and then switching back to DHCP.
My NexusPlayer does something similar...... it's not a permanent solution, as it replicates itself every couple of days, but I just got into the habit of switching back and forth.