Download: Wireshark 1.02 - Network Observation
For analysing network problems Etheral proved it's worth. By now this tool is called Wireshark.
But Wireshark has got a lot more to offer than simple diagnostic functions for the homebound wireless LAN. It is supporting most for the current network protocols and displays collected data by a graphic interface. Should the network be slower than it should be, you can search for reasons: Are data packages lost along the way or are requests ignored? You can even monitor USB and Bluetooth connections.
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