Ahoy, me hearties!
Listen well, me brethren! I’ve just acquired a fine NAS, and I be lookin’ to bolster our magnificent pirate community by sharing me digital plunder far and wide. But alas, it’s come to me attention that the uploads on all me torrents be as small as a speck of sand on the ocean floor, or worse, a big fat zero!
Now, I beseech ye, me shipmates, lend me yer wisdom. How can I fortify our pirate brotherhood? What be the proper settings for me NAS? Be there any trusty trackers or tools to help me upload and distribute the most crucial booty to aid our cause on the high seas?
Speak up, ye seasoned scallywags, and together we shall chart a course toward a stronger, more formidable pirate crew! 🏴☠️🦜⚓
The big problem with disabling µTP is that because it uses UDP, under some kinds of NAT you can get incoming connections despite being NATted. So you will loose some peers if you’re behind a NAT. If you’re not NATted there’s no connectability advantage, because every client that implements µTP can fall back to TCP.
The big advantage to disabling it that you can tweak these things. I don’t know of any client that lets you choose which congestion control algorithm that µTP uses. They all use one called LEDBAT that’s one of the first attempts to design one that avoids “bufferbloat”, i.e. that problem where the torrents fill up the buffers in routers and “clog up the Internet”. That’s nice however it doesn’t work well with networks with a lot of jitter like wi-fi, and it “loses” to algorithms that do fill up the buffer like the default TCP CUBIC. BBR avoids bufferbloat and is designed to keep working well with high jitter—Google’s intention was to make YouTube load faster on mobile phones. It also it wins over CUBIC, which is why almost every seedbox comes configured with no µTP and BBR congestion control. However, because it wins over CUBIC it will “clog up the Internet” in a different way: you may get lower speeds on everything else but don’t lose interactivity.
Linux comes with a different version of BBR that’s tuned to always yield to other traffic called lp. You enable it with
net.ipv4.tcp_congestion_control = lp. I think lp is the optimal choice for seeding public torrents: you give full speed to faraway peers, but only when there’s nobody else that can do it.