Oh, I thought you were pinging your gateway, nevermind. These are the IP's I usually ping in order from closest to furthest to isolate a issue:
127.0.0.1
192.168.0.1
192.168.100.1
Default gateway (found on the DGL-4500 Status page)
8.8.8.8
Google.com
You should get under 20ms all the way up to 8.8.8.8, which is going to depend where you live. Also, don't just do a normal ping, make it at-least 25 packets
Ping -n 25 <IP or domain>