Hope I can help you:
1. Open your browser and enter default IP of the 8817: 192.168.1.1 in the address bar, then press "Enter". Usr&psw will be requested and they are both "admin" by default.
2. On the web interface, go to Advanced Setup-QoS, fill in the details of your device and set the Queue as " Highest".

What details have to be filled. I am not a tech geek. Need some explanation for the fields to be filled.
Thank you

I'm also interested in configuring the QoS for this modem. My current goal is to either 1.) limit the bandwidth for specific data such as video, torrents, or games, or 2.) limit the total bandwidth for one IP regardless of the data type. Any helpful information that would allow me to input the data needed to accomplish one of these results would be greatly appreciated.

For reference here is a screenshot of the TD-8817's (version: 7.1) QoS setup page:
Source 1:
Source 2: http://imageshack.us/a/img4/426/qostd8817.png

Operating System: Windows 7 (64bit)
Modem's Current Firmware Version: 7.0.0 / Build 120509 Rel.32092
Static IPs Configured: Yes
ISP: Frontier Communications (DSL - PPPOE / USA)

i have same problem,need to config bantwidth,looking for anyone for detailed explanation.

After checking the User guide, I find that QOS on this modem is not for Bandwidth control, but it is used to prioritize datas. See here: