I have media stored on a Synology NAS attached to my router. This is accessed by both PCs and laptops running Windows and Linux - some through a switch to the router, some wirelessly, and some via powerline adapters. In all instances where everything else is like for like the same, the Linux machines (running elementary OS) get sustained transfer speeds about 60% of the Windows machines.
For example, my laptop which dual boots Windows 10 and eOS, when plugged directly into the same router as the NAS via an ethernet cable - on Windows gets speeds up and down in excess of 100 MB/s transferring a 3GB .mkv file. On eOS I get around 65MB/s up and around 45MB/s down.
I also have a desktop Windows 10 PC which connects via power line adapter -> router - > NAS which gets uploads of around 11MB/s and downloads of around 3MB/s. On a NUC running eOS, connecting through the same powerline adapter, I get uploads of around 5-6MB/s and downloads around 2.5MB/s. This is also true when I switch the ethernet cable over - so it's not an issue with one cable/port being of lower quality.
The speeds when wired directly wired are faster than SMB1, so I doubt that's the fault. Just in case, I did try editing samba.conf to set a minimum of SMB2, to no change. However, when I set the NAS to reject SMB1 connections I was unable to mount the drives on eOS, despite it seeming unlikely to be restricted to that level based on the speeds available.
I've also tested the eOS on powerline system using AFP to similar results. When testing with FTP I got download speeds nearer to the Windows on SMB, but for whatever reason my Synology NAS won't let me write to drive over an FTP connection and from a quick googling it looks like fixing that is more effort than it's worth when I have SMB working fine, if just marginally slower.
I haven't figured out how to access NFS connections, which don't show up for me under Entire Network in Pantheon Files and I can't figure out the correct input to do a direct Connect to Server. The closest I come is being able to see the shared folders when setting up an NFS connection in Kodi but can't access inside any of them. Again, not something I've rushed to solve considering SMB is already working as desired.
Is this difference in speed just a feature of how Linux handles network shares generally, or is there some tweaking I can do to get speed parity for the bandwidth available on SMB? Do I need to be looking at making NFS work if it really bothers me? Or is this speed difference unique to eOS or perhaps my specific network set up in some way?