What Hardware version is your router? Look at sticker under router.
version is currently loaded? Found on routers web page under status.
What region are you located?
Are you wired or wireless connected to the router?
Have you contacted DDNS to see if you are correctly setting up the router with there settings?
What ISP Service do you have? Cable or DSL?
What ISP Modem do you have? Stand Alone or built in router?
What ISP Modem make and model do you have?
If this modem has a built in router, it's best to bridge the modem. Having 2 routers on the same line can cause connection problems.
To tell if the modem is bridged or not, look at the routers web page, Status/Device Info/Wan Section, if there is a 192.168.0.# address in the WAN IP address field, then the modem is not bridged.
If the modem can't be bridged then see if the modem has a DMZ option and input the IP address the router gets from the modem and put that into the modems DMZ.
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.