Changing the mtu size in windows vista, 7 or 8. setting the mtu size: once the command prompt window is open follow the steps below to change the mtu size: type netsh interface ipv4 show subinterface; press enter. you will see a list of network interfaces.. If the reply you get is “packet needs to be fragmented but df set.”, then you have to try a lower mtu value. keep decreasing the value by 10, i.e. 1490, 1480, 1470 until you get a successful reply.. You must make sure you change the mtu on the correct network adapter associated with your broadband connection or vpn client. you must also reboot your computer in order for the new settings to.
Correcting a mtu issue: the first step in correcting a possible mtu issue is to contact your isp (internet service provider). ask them what their mtu is set to. this way you can adjust your router to the same settings. adjusting the router’s mtu is the best solution because it avoids the need to adjust individual devices.. In the mtu size field, enter a value from 64 to 1500. click the apply button. your settings are saved. if you suspect an mtu problem, a common solution is to change the mtu to 1400. if you are willing to experiment, you can gradually reduce the mtu from the maximum value of 1500 until the problem goes away..