D-Link DIR-822 User Manual page 134

Section 7 - 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 (192.168.0.1) and click OK.
• Enter your username (admin) and password (previously specified. Click Login to enter the web configuration
page for the device.
• In the Settings menu on the bar at the top of the page, click on Internet and then go to the WAN page. From
there click on Edit and go to the All Settings tab.
• To change the MTU, enter the number in the MTU field and click Apply to save your settings.
• Test your email. If changing the MTU does not resolve the problem, continue changing the MTU in increments
of ten.
D-Link DIR-822 User Manual 130