@MrMazda No, I'm not using any kind of VPN. I'm using my home internet connection.
I have to say that everytime I turn on my PC, the download speed goes up to 10 MB/s for like 5-10 seconds, and then it goes back down to 50-200 KB/s

My Transmission's port test returns closed except when checking from an outside source (http://www.canyouseeme.org/ like in the minitutorial) it returns OPEN.

It's completely frustrating, because i've been a good while with this and the upload/download speeds are straight up pathetic.

Thanks,