I need a file transfer protocol that works across networks (using my IP) so I can access my files. It would ideally have good native support in Windows and Linux and fast transfer rates and credential support on my server's end. At the moment, the server that I'm looking to access is connected via gigabit ethernet to my router where I receive these speeds. Obviously the upload speeds are not fully ideal but they should be sufficient. I have tried FTP (using proftpd - the server is Ubuntu Server 18.04) but it was honestly too slow for me to bother with. My drives are more than capable as I am able to fully saturate my local gigabit connection with SMB - I know gigabit is a lot more than 20Mbps but I would honestly expect more than 300KBps with FTP. Any help would be appreciated, thank you.