Sftp run slow and view thumbail

Hi,

I have some NAS and Proxmox servers. I test and it is result:

Local network / Firewall pass / No bandwidth limited.
sftp protocol with port 211
Only 5mb/s

Same condition but i map with Raildrive
Speed 50mb/s

Any ideas? May be Raidrive use cache or something els? Also, i may view thumbnail with Raidrive

I think your team may take care this?