So you blame Riot but not your your isp, the isp's between you and Riot since none of those things can be causing the problem right? I mean obviously you've got a direct connection to Riot's servers straight from your house and you don't need an isp the might route you through several other isp's at all correct. Sicne you obviously don't have a direct connection to Riot's servers that means it's not Riot's servers but one or more isp's between you and them causing the problem.
Now given that it's not Riot's servers as shown above why don't you follow the suggestions in the support forums for doing a tracert test and submitting it to Riot so they can find out where the problems at. You can also just keep on blaming Riot for not getting your problem solved and nothing will change.