you cannot improve the server latency of your games if the source of the problem is actually the server and how your internet service provider DNS is connected with them. im sorry but the power line will not help you improve. we are at their mercy.
only things we can do is
** restart your router
** refresh your internet settings (e.g. disbable/reenable network adapter, run commandlines like "ipconfig /flushdns","ipconfig /renew" or "netsh winsock reset")
** get a less congested bandwidth. if youre wireless at 2.5Ghz go to teh 5.0Ghz connection. if youre wired or have a limited internet plan like a 30Mbps line, then make sure nobody else is download at max speed or continously using netflix for example while you are playing games.
**...