To change the MTU
rate on your router follow the steps below:
Open your browser, enter the IP address of your router (192.168.0.1) and click OK.
Enter your username (admin) and password (blank by default).
Click OK to enter the web configuration page for the device.
Click on Setup and then click Manual Configure.
To change the MTU enter the number in the MTU field and click Save Settings.
If changing the MTU does not resolve the problem, continue changing the MTU in increments of ten.
1500 is the default MTU for Dynamic (DHCP) Cable (p. 20 in user manual).
1492 is the default MTU for PPPoE (Point to Point Protocol over Ethernet) DSL (p. 22 in user manual).
Other MTU settings are listed in the manual, simply do a search for "MTU".
Note: AOL DSL+ users must use MTU of 1400.
To find the proper MTU Size, you'll have to do a special ping of the destination you're trying to go to. A destination could
be another computer, or a URL (p. 86 in user manual).
Here is the PDF link to the User Manual