An option to randomly change the port periodically, automatically.

[vnicolici]

Suggestion

It would be nice to have an option to set a time interval for automatic random port changes in the settings, for example every 30 minutes or every hour.

Use case

I have a connection that on average is about 600Mbit down, 200Mbit up. While I have no problem achieving consistent uploading with qBittorrent close to 200Mbit, the downloads have issues reaching 600Mbit consistently, usually they were also around 200Mbit.

I've been fighting with download performance issues over the last few days. I've experimented with various settings but nothing helped much. When I change settings and restart qBittorrent, sometimes the performance greatly improves. But it doesn't last long, after about 30 minutes to one hour or so the performance goes slowly down.

Yesterday I discovered that changing the port temporarily restores restores the performance for about an hour. So now, every hour, I randomly change the port, manually. The problem is that sometimes I need to sleep or leave the house, so I can't change the port all the time, that's why an option to do this automatically would help.

Now, about this behavior, I'm not entirely sure what triggers it. It could be my ISP detecting bittorrent traffic and throttling it. It could be peers hammering my port trying to connect, and lowering my performance. Or, it might be normal. After a while the peers might detect that my upload speed is only 200MBit and will start uploading to me at a similar speed. But I kind of doubt that is the problem.

So, not sure if changing the port like this is a healthy thing for the bittorrent "ecosystem", but if it doesn't cause issues would nice to have this option.

I found some workarounds on the Internet involving using the web-ui with some cron jobs to achieve this, if I understood correctly, but as I'm running qBittorrent on Windows that would be a bit more difficult to implement. Basically I would have to create a script that chooses a random number for the port from a range of unused ports, then do a curl to the API that changes the port, then schedule that script to run periodically. Alternatively, I could link that script to some event, for example finishing a download, but I don't think that would be a great idea.

Attached is a screenshot with the current behavior. On the left you see it starting up and achieving over 40MB/s 320Mbps download speed initially. After about one hour and a half, the speed drops to around 16MB/s, under 160Mbps. After 6 hours, I changed the port. After a few minutes that change brings the speed to about 64MB/s 512Mbps. After about an hour, the speed started to drop. I changed the port again, it recovered to 64MB/s again. An hour later, the same thing, it started dropping, I changed the port, it recovered to 64MB/s.

Then I went to sleep for about 8 hours. In that interval, without port changes, the speed fluctuated around 20MB/s, similar to the upload speed, with rare spikes higher than that. Then, after I woke up, I started changing the port again every hour. While that didn't work as well as yesterday, I still saw improvements in speed after changing the port, with the speed going over 50MB/s, 400Mbps.

Extra info/examples/attachments

[vnicolici]

Right now, I'm less inclined to consider this a useful feature for my particular use case. I'm concerned that by doing those port changes I'm taking too much from the BitTorrent community without giving enough back. For the last few days I have refrained from changing my port manually. So far, I have 10.6 TB downloaded and 8.5TB uploaded. I would probably have more downloaded if I changed my port repeatedly, but I don't think that would have been fair.

That being said, this feature might still be useful for other people that have issues due to their ISP or other limitations, so this feature might still make sense. As for me, I can live without it.