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!


Are you sure nothing else is changing? How long did you do these tests for?
I’m completely sure! Yesterday it was running ok all day. Today, I port forwarded and left home for a couple hours, after coming home I checked the computer and saw the low speed. The first thing I did was think about what had changed and I closed the ports. The speed went up immediately. I tested it a couple more times with different ports and the same thing happened.
What the fuck?
Maybe they meter incoming speed? Try running a speedtest using a web server or iperf3 or something.
more likely they just know it’s bittorrent traffic. that’s not hard for an ISP to sniff out, if you aren’t using a VPN. it’s not uncommon for ISPs to throttle bittorrent traffic automatically.
And the reasons they do it run the gamut from ‘mildly shitty’ to ‘profoundly shitty’.
You might consider routing torrent traffic through multiple old garbage laptops on your network, then putting your regular traffic through on an ‘unforwarded’ looking computer at full speed? Might work.
I’ll look into it, but I don’t think this is something I would be capable of doing. Would a couple of raspberrys work?
Yeah but ancient secondhand laptops are about the same price, come with storage, and you’re taking ewaste out of circulation.
That’s a great point!
Reduce, reuse, recycle, steal shit!
I would really like avoiding a VPN. Money is tight rn and it’s another payment at the end of the month.
Understandable, but without one you’re totally at the mercy of your ISP. If it turns out they are automatically throttling BitTorrent traffic, there’s nothing you can do without a VPN because on a fundamental level they control your access to the internet. The unfortunate thing about BitTorrent is that it’s not sneaky at all. Your ISP will be able to tell you’re doing it if you aren’t encrypting that traffic.
Yeah, I think I’m just delaying the inevitable. I’ll call the ISP in a couple hours and maybe it will be time to look for a christmas deal with airvpn.
The speed test looks fine. Maybe they meter it as you say. Guess I’ll have to contact them so they can explain wtf is happening to my connection.
How did you do the speed test? You need to have an open port on your side and another IP address outside your network.
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.
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!
Its identical ish to what you’d do if you host a website. You can also do that and just try downloading a large file from it (still while outside your network)