have you got any other devices connected to the router that would be a priority? Like an XBox or something ?
Are you downloading or uploading torrent files ?
What about the connection ?
Is it wired or wireless? Try wired if currently wireless.
Other things can be the cause too, such as ISP , or ISP traffic. Or someone may be using your internet thru wifi. Is your connection secure ?
It might be the server too, if others are seeing the same thing then server may be the cause.