Change your router's oil every three months or six thousand petabytes, whatever it comes first, some models may require maintenance sooner than you expect or plan, others may run forever and become difficult to find where the heck are they located.
Some devices designed in Japan have the tendency to randomly increase out of control the speed of your interfaces, if you experience that problem send them to the factory for refurbishing and to be resold to a poor ISP. Never, ever, clean fiber optic connectors with spit ... J
