Maximum Transmission Unit (MTU) is the maximum size of data allowed in one packet before it's received through a connection. If the MTU value is too large, your computer has to break down the packets into smaller parts. Called packet fragmentation, this process can dramatically slow down a connection when transferring a large amount of data. The MTU size for a dial-up connection is considerably smaller than for its broadband counterparts. Generally, an MTU size of 576 is optimal for a 56k dial-up connection. Lowering the MTU to a size your modem can easily work with prevents packet fragmentation and allow you to maximize your connection. Use the Windows Command Prompt to assign a lower MTU value.
Instructions
Locate Name of your Network
1. Press the "Windows" and "R" keys simultaneously on your keyboard. This opens a "Run" box.
2. Type "Control netconnections" and click the "OK" button. This opens a new window on your screen displaying your network connections.
3. Write down the name of the dialup connection and close the window.
Change the MTU
4. Click "Start" and type "CMD" in the "Search" box.
5. Right-click "CMD" from the search results and click "Run as administrator." Click "Yes" on the "User Account Control" dialog box. This opens a Windows Command Prompt.
6. Type "netsh interface ipv4 set subinterface "Name of Connection" mtu=576 store=persistent" and then press "Enter." Replace "Name of Connection" with the name you noted down in the first section (do not include the quotes).
7. Close the Command Prompt and restart your computer.
