I have a gigabit connection between my PC and my server (iperf3 tests show ~930Mbps) and I want to be able to transfer large files as fast as possible. The hard drive on the server is connected via USB3 and it is a Rock64. With ssh (I am using btrbk with ssh) I think the bottleneck is probably ssh because of high CPU usage and hot temps (~60C). I did disable compression although I think it's disabled by default (put it in ~/.ssh/config). I only got speeds of up to 350Mbps maximum but it fluctuated a lot, I don't think the Rock64 can handle the ciphers with that much data. And after a while it slowed to a crawl (less than 1Mbps) for some reason that I'm not sure of. Restarting the transfer worked. (May not be relevant to the question).
I need a cipher that can do about 480Mbps at the least. You can probably lower that number by a bit due to realistic USB3 speeds though. Not too worried about security because it is just Ethernet connections from PC > router > server but no/weak encryption would be overkill anyway. So preferably the most secure cipher that can do above speeds.
And after a while it slowed to a crawl (less than 1Mbps) for some reason that I'm not sure of.
That sounds more like the drive being the bottleneck. Is it actually just some lame thumb drive? Also the bus speed of USB 3.0 is 5Gbps (i.e. 5000Mbps).