D-Link DFL-600 - Manual (Page 43)

If you have some PCs (or other network devices) that do not require RADIUS
user authentication to access the WAN (Internet), you can enable 802.1x, and
then enter the IP Address and IP (subnet) Mask of these devices under the
Edit link (which will appear when you enable 802.1x). PCs and network
devices that have their IP Address and IP (subnet) Mask entered on the
802.1x Device Configuration page will be allowed to access the WAN
(Internet) by the DFL-600 without any RADIUS user authentication,
effectively bypassing the RADIUS user authentication step.
Clicking the RADIUS click box will open the following page: