This usually is happening with the ISP's hardware, or somewhere in between.

If you want to see action taken on it, you will need to contact your ISP. If they aren't aware enough of what FFXI is doing because it hasn't already been reported, you may need to track the state of your connections with something like Netstat or TCPview, then run tracerts to those connections in "WAIT STATE" to see which ones are stalling, then forward that to your ISP for investigating.

We recently ran into this very problem with BT and O2 subscribers last month, and it was due to a failure with a large segment of their contracted network partners. The thread is still up on the first page of this forum:
http://forum.square-enix.com/ffxi/th...0011-3001.-WTF