I have a Raspberry Pi 4 with 8GB RAM and it's running Ubuntu 20.04.  It has gigabit ethernet built in.  The router everything's connected to is an Asus RT-ACRH13.  The computer is a Dell Optiplex 7010 with Kubuntu 22.04.  Everything's connected at 1Gb/s but I'm only getting about 46 MiB/s when transferring files from the Raspberry pi.  The files are stored on a 2TB Hdd connected to the Pi via USB3.   How can I get faster speeds from the Raspberry Pi?

Thanks