You can either configure your router so ALL devices on your home network use it, OR just alter the config of each device that you want to use Smart DNS Proxy.
If it is a T8-S Plus device that you ordered, click the icon of two little cogs on your homescreen (settings).
Click the NETWORK icon. You'll now need to select Ethernet or Wi-Fi (depending if you have a network cable for your internet access on the DroidBOX or not).
If Ethernet: Click the Advanced Options entry. IP Settings change to Static.
You now need to enter the details (something like 192.168.SOMETHING.SOMETHING for the IP address,
Gateway is your modem/router's IP address, most often 192.168.1.1 , 192.168.0.1, 192.168.1.254 or 192.168.1.240
normally Network prefix length is normally 24 (Newer way of expressing a netmask of 255.255.255.0 )
Finally you get to the DNS section, enter in the IP addresses the company's guide ask you to.
The above is from memory, but it should follow those steps approximately.
If you're using WiFi, same again but select Wi-Fi at the start, and you'll first need to click on the WiFi network you're using I believe.
If it is a T8-S (not the Plus model), click on the Settings icon again, this time click on the "OTHER" tab, then the MORE SETTINGS button. From here, select WiFi or Ethernet and again you'll need to manually specify the values required, rather than using DHCP.