D-Link DIR-640L User Manual page 114

Section 9 - Troubleshooting
You should start at 1472 and work your way down by 10 each time. Once you get a reply, go up by 2 until you get a fragmented
packet. Take that value and add 28 to the value to account for the various TCP/IP headers. For example, lets say that 1452 was the
proper value, the actual MTU size would be 1480, which is the optimum for the network we're working with (1452+28=1480).
Once you find your MTU, you can now configure your router with the proper MTU size.
To change the MTU rate on your router follow the steps below:
• Open your browser, enter the IP address of your router (http://192.168.0.1) and click OK.
• Enter your username (admin) and password (should be left empty). Click OK to enter the web configuration
page for the device.
• Click on Setup and then click Manual Configure.
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