Enjoy.
Some things to try:
Ensure DNS IP addresses are being filled in under Setup/Internet/Manual? You can find these under Status/Device Info/Wan section.
Turn off ALL QoS (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.
Turn on DNS Relay under Setup/Networking.
Setup DHCP reserved IP addresses for all devices on the router. Setup/Networking
Ensure devices are set to auto obtain an IP address.
Set Firewall settings to Endpoint Independent for TCP and UDP.
Enable uPnP and Multi-cast Streaming under Advanced/Networking.
Try single mode G or mixed G and N?
Preferred security is WPA-Personal. WPA2/Auto TPIK and AES.
Any other WiFi routers in the area? Use
InSSIDer to find out.
Turn off Short GI and Extra Wireless Protection if you have it. Under Advanced/Advanced Wireless.