D-Link DIR-850L User Manual page 140

Section 6 - Troubleshooting
3. Why can't I connect to certain sites or send and receive emails when connecting through my router?
If you are having a problem sending or receiving email, or connecting to secure sites such as eBay, banking sites, and Hotmail,
we suggest lowering the MTU in increments of ten (Ex. 1492, 1482, 1472, etc).
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.
• Click on Start and then click Run.
• Windows® 95, 98, and Me users type in command (Windows® NT, 2000, XP, Vista®, and 7 users type in cmd) and press Enter (or
click OK).
• Once the window opens, you'll need to do a special ping. Use the following syntax:
ping [url] [-f] [-l] [MTU value]
Example: ping yahoo.com -f -l 1472
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).
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