Hello there,
it's been a long time when I started to benchmark different FW/HW combinations. I had some time to summarize the numbers, but maybe a few of you won't surprise.
The image contains all the numbers spiced with a few DD and 100Mbit ETH measures as well. Mostly a standard vfat file system was in use with 1 Gbit of connection speed, but I'm using f2fs in most of my devices, so I couldn't skip that flash friendly file system. Where the ethernet speed (100 Mbit/1000 Mbit), file system (f2fs/vfat), way of method (dd/ftp) differs it's mentioned in the description.
Downloading bigger iso files with Filezilla (between 400-800 MBs) from my Transcend 790K flash drive was the base, running 3 times, the best time was marked. I'm so surprised how fast TP-Link's vsftpd implementation is.
Spreadsheet on Google Drive: https://docs.google.com/spreadsheets/d/1rEBjANh43ZPL4Jh4rQF5bH9DXNxtoLysopKtt4pP3Nk/edit?usp=sharing