Yesterday I changed my ISP to one that allows port forwarding. Today the port forwarding has been enabled by the company and I set it up on the router.
After enabling it, my download and upload speed dropped from peaks of 50 MiB/s and valleys of 4-6 MiB/s to a very stable 2 MiB/s. Nothing else has changed in my qBittorrent configuration. If I close the ports again, the speed goes back to normal. I checked if the ports were open on various websites and all of them show that they are forwarded.
I was looking forward to be able to port forward and connect with every possible peer for years, and today has been a big disappointment in that regard!
Has anyone else seen something like this and if so, can you point me to the right direction to fix the problem?
Edit: Thanks everyone for your time and your help! Still working on it, but it’s heartwarming to be on the receiving end of the goodwill of this community.
Sometimes I love the internet!


Ah, I used the speedtest tool of cloudflare, ookla and openspeedtest. You are referring to https://iperf.fr/, right? When I get home I’ll read how to do it properly!
I am a Unix person I just get it from my distro:s package repository. I don’t know if that URL is the correct address.
The steps are (simplified):
This specifically speedtests incoming connections to your IP address. Regular speedtests like fast.com, etc. Test outgoing. With the way TCP/IP works, your ISP can easily differentiate the two.