Try 1492 and if it doesn't work keep going down by 10 (1482, 1472, etc..) ping www.cantreachthissite.com -f -l 1472 http://www.richard-slater.co.uk/archives/2009/10/23/change-your-mtu-under-vista-or-windows-7/

Hi, I observe big size (1514 bytes+) packets drop at Windows 7 machine. I have two Windows 7 machines (A & B) connected through wifi infrastructure mode. Machine A pings to B with 1514 bytes+ packet but no reply from B. I checked using at Netmon and Wireshark at machine B. Netmon shows 1514 bytes+ packets are received at machine B but Wireshark does not show any packet and netstat -s does not show any increments in discarded/error counters. I tested with Intel and Broadcom both but same result. I set mtu size 2000 on both machin using netsh command but still same result. Could you please let me know how to debug this issue or Windows 7 issue (which is unlikely)? Regards, Anand Choubey

Try 1492 and if it doesn't work keep going down by 10 (1482, 1472, etc..) ping www.cantreachthissite.com -f -l 1472 http://www.richard-slater.co.uk/archives/2009/10/23/change-your-mtu-under-vista-or-windows-7/

I am having the same issue but on win2k8r2, 1468 seems to be the magic number when you are in a vlan tagging env the 802.1q adds overhead which exceeds the mtu. even if you increase the mtu above 1500 it will drop the packets. there are other tweaks you can do to the registry such as: EnablePMTUDiscovery at least for me on win2k8r2, reducing the mtu to 1468 on my server solved the problem, when I test anything where one side or the other (client/server) is a trunk port, it fails. access port to access port works fine, crossover or default vlan (no tagging on trunk port) works. here is a ref for you: http://msdn.microsoft.com/en-us/library/ee377084(v=bts.10).aspx

I am having the same issue but on win2k8r2, 1468 seems to be the magic number when you are in a vlan tagging env the 802.1q adds overhead which exceeds the mtu. even if you increase the mtu above 1500 it will drop the packets. there are other tweaks you can do to the registry such as: EnablePMTUDiscovery at least for me on win2k8r2, reducing the mtu to 1468 on my server solved the problem, when I test anything where one side or the other (client/server) is a trunk port, it fails. access port to access port works fine, crossover or default vlan (no tagging on trunk port) works. here is a ref for you: http://msdn.microsoft.com/en-us/library/ee377084(v=bts.10).aspx