When a qBittorrent torrent client (A) shares a file (Seeding == A), the attacker implemented UDP flooding on the IP and PORT used by Qbittorrent. As a result, file sharing was not possible, and other users who were downloading the file were also disconnected from Seeder(A). However, the Internet speed in the network was normal, and the Internet speed of the attacked user (A) was also slightly slow in the normal range. The users who downloaded the file were in the wireless LAN environment, and the attacker and Seeder (A) were in the wired LAN environment. What do you think is the reason? No matter how much I think about it, I do not understand that only the torrent client is slow and the internet speed is normal.
Given the vague description it's impossible to know for sure. But perhaps what the question is aiming at is that not all denial of service attacks target the network.
DoS attacks overwhelm a target system until something breaks. Sometimes it's the network, but it can also be other things. Maybe in this case, the machine running the client was overwhelmed before the network did by running out of a resource like CPU or memory.