D-Link DSL-2750E User Manual - Them. See At Figure 1-18

For Windows XP, You’d better check as follows. 

(1)  Whether the provided ETHERNET cable between the D-Link DSL-2750E 

and the computer is in the correct type. 

(2)  Whether the ETHERNET card works normally. For Windows XP, Select 

Start > Setting > Control Panel > System > Hardware > Device Manager

. For 

Windows 7, Select 

Start > Control Panel > System & Security > Device 

manager

 Check whether there are devices that have the “?” Or “!” Mark 

under Network adapters. If such devices exist, uninstall and then re-install 

them. See at Figure 1-18 

18