What Hardware version is your routers? Look at sticker under router.
What Firmware versions is currently loaded? Found on routers web page under status.
What wireless modes are you using? Under Setup/Wireless/Manual.
Try single mode G or mixed G and N?
Try single mode G or mixed G and N on 2.4Ghz and single mode N on 5Ghz?
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 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.
Some things to try:
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.
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 under Advanced/Firewall.
Enable uPnP and Multi-cast Streaming under Advanced/Networking.