D-Link DIR-615 User Manual page 101

Section 6 - Troubleshooting
3. Why can't I connect to certain sites or send and receive e-mails when connecting through my router?
If you are having a problem sending or receiving e-mail, or connecting to secure sites such as eBay, banking sites, and web
email, we suggest lowering the MTU in increments of ten (Ex. 1492, 1482, 1472, etc).
Note: AOL DSL+ users must use MTU of 1400.
To find the proper MTU Size, you will 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.
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• Windows 95, 98, and Me users type in command (Windows
and XP 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, let's say that 1452 was the proper value,
the actual MTU size would be 1480, which is the optimum for the
network current network (1452+28=1480).
Once you find your MTU, you can now configure your router with
the proper MTU size.
D-Link DIR-615 User Manual
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