MTU
There is kind of a work around to detect MTU problems with TCP using ICMP as a base: http://en.wikipedia.org/wiki/Path_MTU_Discovery PMTU. The caveats are: it doesn't work with UDP, and some scenarios with ICMP being blocked or old operating systems, and some interoperability/network topology situation The problem comes when you want to send more data over this connection - lets say you wanted to send 3000 bytes: your computer would split this up based on your MTU - in this case, two packets of 1500 bytes each, and send them to your ADSL modem which would then split them up so that it can fulfill its MTU. Now your 3000 byte data has been fragmented into four packets: two with a payload of 1492 bytes and two with a payload of 8 bytes. This is obviously inefficient, we really only need three packets to send this data. Had your computer been configured with the correct MTU for the network, it would have sent this as three packets in the first place (two 1492 byte