I've been using mobile internet for last few years and whenever i would try to seed it'd be like 0.2 kb/s at best. I know that it's due to my dynamic IP (or whatever it's called) and i have closed ports.
Then i saw some people say that opening your ports makes your connection better/faster because you're able to connect not only to people with open ports, but closed ones aswell. Does it make sense download-speed-wise? Because how could i take traffic from someone who's unable to seed due to closed ports?
An open (or closed) port has nothing to do with speeds. An open port won’t be faster.
Opening ports lets others connect to you. If one party has an open port (but the other does not), a link can still be made between the two clients. If neither have an open port, neither will make a connection (no transfers). If both do, then either can negotiate the transfer. So at least one needs to be open.
The speed is the speed. Mobile internet tends to be terrible and I imagine upload speeds are heavily capped. Ports don’t help here.