Welcome to this user forum.
I have moved your post to this new thread, so you can get personal help from the community, so please watch this thread for updates.
modem should work without a problem did you set username and password in router
username bthomehub@btbroadband.com
password BT
Are you using the DM200 in conjunction with the Nighthawk or are you trying to use it standalone? If you are using it with the Nighthawk you need to configure it in bridge mode.