D-Link AC3200 Ultra User Manual page 210

Section 8 - Troubleshooting
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
D-Link DIR-890L User Manual 205