Hi there, you gave a lot of unnecessary info there, unrelated to your problem, but you did not give additional info directly related to your actual problem that will help us answer your issue. I will now ask you the questions that will help.
Does your slow speeds issue happen when you are using a device that is connected to your modem with a wire, or does it happen on devices that are connected wirelessly, or both?
how far is your modem from the room you most often use your devices in? is it in the same room, next room over, or is it 2 floors down in your basement?