Try to reboot the ONT. Just for grins and giggles, shut off the router first.
Unplug the BBU power supply. You may hear the BBU go into alarm mode.
Open the BBU to expose the battery. Remove a wire from the battery terminal. Wait a couple of minutes, not seconds, but minutes.
Reconnect the wire to the battery terminal. Close the BBU battery cover.
Plug in the BBU power supply.
Turn on the router again. See what difference it made.
If no difference, post back with details of service tier and speedtest results on a wired connection. Don't worry about wireless until wired is good first. What D-Link router model did you have, and is it different than the D-Link from your friend?
Be prepared to log in to the router to look for several things, including first two WAN IP address octets.
Use »
myspeed.visualware.com/ for speedtest. Select the nearest server to you.