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!
Man, if this is the simplified version, I'm totally fucked. I understand every word, but the order in which they are stringed together confuses me.
I'm waiting for a call of my ISP's IT service to see what's what. If they can't (or won't) fix my issue, I'll bite the bullet and I'm gonna buy a subscription to a VPN.
Thank you for the detailed explanation!