Try the following:
Has a Factory Reset been performed? You might try this then follow the below suggestions...
Some things to try: - Log into the routers web page at 192.168.0.1.
Use IE, Opera or FF to manage the router.Turn off ALL
QoS or Disable Traffic Shaping (DIR only) GameFuel (DGL only and if ON.) options. Advanced/QoS or Gamefuel.
Turn off Advanced DNS Services if you have this option under Setup/Internet/Manual or under Setup/PARENTAL CONTROL/Set to>None: Static IP or Obtain Automatically From ISP.
Enable Use Unicasting (compatibility for some ISP DHCP Servers) under Setup/Internet/Manual.
Turn on DNS Relay under Setup/Networking. Link>
Finding Faster DNS Addresses using Name BenchSetup DHCP reserved IP addresses for all devices ON the router. Setup/Networking. This ensures each devices gets its own IP address when turned on and connected, eliminates IP address conflicts and helps in troubleshooting.
Ensure devices are set to auto obtain an IP address.
Enable uPnP and Multi-cast Streaming under Advanced/Networking. Disable uPnP for testing Port Forwarding rules.
Set current Time Zone, Date and Time. Use an
NTP Server feature. Tools/Time.
Links>
Wireless Installation Considerations and
Managing Signal Congestion Ensure the default (dlink) SSID name is changed. Can be anything and not something thats already in use by any neighboring WiFi routers. Under Setup/Wireless/Manual.
What wireless modes are you using?
2.4Ghz Routers only: Try single mode G or N or mixed G and N?
Channel Width set for Auto 20/40Mhz or try 20Mhz only.
Try setting a manual channel to a open or unused channel. 1, 6 or 11. 11 for single mode N if the channel is clear.
What security mode are you using?
Preferred security is WPA-Personal. WPA2/AES Only. Some WiFi adapters don't support
AES, so you might want to try
TPIK only or Auto.
Any other WiFi routers in the area? Link> Use InSSIDer to find out. How many?