I also confirm the behavior described by some users above.
I did a long battery of tests at home, and have the following numbers:
SFTP: <100Mbps - expected because of encryption which maxes out my server CPU
I have similar results with my iPhone, iPad Pro or my AppleTV 4K.
I haven’t checked NFS though.
My WiFi coverage is excellent (Wifi 5, 2.4+5GHz) and I even performed these tests having my mobile just a few inches from my access point to make sure that there is as few interference as possible.
Obviously, I cannot check the numbers with an Ethernet connection as none of these devices have an Ethernet port.
I also tried every possible flavor of SMB (2, 3, as SMB1 is disabled for security reasons on my server) on Infuse but the results are roughly the same.
The only sensible comparison was with my MacBook which has a WiFi connectivity close to my iPad Pro.
It uses the SMB client embedded in macOS and I manage to achieve consistent speeds of around 300Mbps on the very same files.
For the sake of completeness, my SMB server is based on an NVMe SSD and CPU usage when streaming to Infuse never goes over 15%.
Of course, I am not expecting to be exactly on par with FTP/Jellyfin in terms of throughput, as SMB is more verbose, but here we are talking about 25% of the performance, or less than half the speed I manage to achieve on the very same files on my Mac.
I’ll try to check the numbers with the iOS embedded SMB client later on, to compare with Infuse SMB client on the very same device and report back.