I have a transmission daemon (3.0) running on a Raspberry Pi4 (bullseye). When the download bandwidth is limited to 1MB/s, everything is fine, torrents are downloaded, remote gui can connect to the daemon, web interface accessible. However if the speed limit is 1.5MB/s or higher, after a certain time the daemon hangs;, i.e. no connection possible and download also stops (this is seen because the external HDD spins down). There is no high CPU load, the other network connections of the RPi are working, nothing strange, except transmission being not accessible. Only restart solves the problem.
What can be the problem?