Change the MTU and RWIN Settings Intended For Windows Me Windows 98 Windows 95 You may be aware that the performance of Dial-Up Networking can be modified by changing a few numbers, known as MTU and RWIN. Although this is easy in other Windows Sockets Stacks (such as the popular Trumpet Winsock), the setting isn't obvious in Windows' Dial-Up Networking. Note that if you don't know what these numbers mean, then you don't need to change them, and this information does not apply to you (however, see notes following for exceptions). Here's how to change these settings: Run the Registry Editor (REGEDIT.EXE). Open HKEY_LOCAL_MACHINE\ System\ CurrentControlSet\ Services\ Class\ Net\. Under that branch, find a key (numbered, such as 0005) that contains has TCP/IP assigned to the DriverDesc value. Select New from the Edit menu, then String Value, and type MaxMTU for the name of the new value. Double-click on the new value, and type in the desired number - 1500 is the default. Then, open HKEY_LOCAL_MACHINE\ System\ CurrentControlSet\ Services\ VxD\ MSTCP\. Again, select New from the Edit menu, then String Value, and type DefaultRcvWindow for the name of the new value. Double-click on the new value, and type in the desired number - 2144 is the default. Note: This will only work if you are using PPP (and not SLIP) with Dial-Up Networking. Using this method with SLIP will set the MTU to 58, regardless of your MaxMTU setting. Note: If you are experiencing problems such as your browser stopping in the middle of a page, an MTU value of 576 might fix the problem. Written by: Annoyances.org Last updated: Friday, November 16, 2001 Care to discuss this article with other Windows users? Select your operating system here, and click Continue to post your question. - Choose your OS -Windows 7Windows VistaWindows Server 2003Windows XPWindows 2000Windows MeWindows 98Windows 95 Previous discussions about this article: (open a message to see applicable responses, if any) [Windows XP] Question about 'Change the MTU and RWIN Settings in Dial-Up Networking' (steve: Friday, October 26, 2001) [Windows 98] Question about 'Change the MTU and RWIN Settings' (Eddy: Monday, December 31, 2001) [Windows 98] Question about 'Change the MTU and RWIN Settings' (Leslie Dreier: Saturday, July 13, 2002) [Windows 2000] HOW-TO set MTU in Windows 2000 and NT4 (Nate: Friday, November 8, 2002) [Windows 95] Question about 'Change the MTU and RWIN Settings' (Art: Wednesday, November 20, 2002) [Windows 98] Question about 'Change the MTU and RWIN Settings' (don: Wednesday, December 11, 2002) [Windows 98] Comment about 'Change the MTU and RWIN Settings' (Peter Borkuti: Thursday, January 16, 2003) [Windows XP] Question about 'Change the MTU and RWIN Settings' (l. Varcoe: Saturday, September 25, 2004) [Windows XP] Question about 'Change the MTU and RWIN Settings' (franco: Sunday, July 3, 2005) [Windows Vista] 'Change the MTU and RWIN Settings' in Vista? (Paul Speller: Wednesday, September 13, 2006) [Windows 98] Question about 'Change the MTU and RWIN Settings' (Sam Lee: Sunday, December 17, 2006) [Windows Vista] Question about 'Change the MTU and RWIN Settings' (ghussan: Tuesday, May 15, 2007) Return to "Networking, Internet, & Administration"