So this issue seems to be a new one in the latest versions of Ubuntu, a slow internet connection is a real pain in the ass but after relentless network testing and checking I have every update installed and yada yada I never thought to check the MTU (maximum transmission unit) which of course was set too high, this means that for wireless networking any packets larger than the default MTU (1492) will get lost in the network. Bad times, LUCKILY you can set this yourself!
its recommended that you test from 1499 down, I got to 1464 before my network seemed ok.
Run this command and keep lowering the value until you stop getting the message “Frag needed and DF set”
Run the below in your terminal:
sudo ifconfig eth0 mtu 1464 ifconfig | grep MTU
This lowers the maximum packet size and it sped my network speed up from around the 20kbps mark to my Windows 7 speed which is around 4mbps.
So mine started to slow down again, which really sucks and this is a reported Kernel 3 bug, BUT if you set your wireless router to NOT send a wireless N signal it will speed up brilliantly!