More trouble with the Vonage device. The audio quality has become unacceptable. Obviously, my previous setting of putting the Vonage router behind the Airlink Router and setting it to QoS didn't work well.
After talking with Vonage technical support for nearly 1 1/2 hrs, I was asked to put the Vonage in the DMZ of the router, which means it would have to defend for itself without the firewall. As it turns out, the QoS feature sacrifice too much of the bandwidth; it was getting only 2.5Mb/s download and 0.25Mb/s upload. This was the reason for the poor audio quality. By placing the Vonage router in the DMZ, it's getting roughly 15Mb/s download and 5Mb/s upload. Evidently, the computers are getting good speed as well.
The trick is to set the Vonage in static IP address; we use 192.168.1.130. You can do this by placing a computer behind the Vonage router in DHCP mode and log into 192.168.15.1 with User name of "router" and password of "router". And then go into the "Basic Setup" and select "Static IP Address" in the "Connect Using" drop down. Enter 192.168.1.130 in the IP address, Subnet Mask of 255.255.255.0 and default gateway and primary DNS of 192.168.1.1. For the Secondary DNS, I was told to use 220.127.116.11, probably just a dummy IP address. And then click Apply. The router needs to be rebooted followed by the rebooting of the Vonage device. Also, you may need to reboot the computers or disable/enable the network that were originally connected to the router. This wasn't a smooth and easy setup. But I finally got it to work. Not a task for the faint of heart. How do other laymen handle this kind of the problem? It's just amazing.
By the way, the following websites are great for checking speed: speedtest.net and mycooltools.com and click on myspeed.