File transfer from Android phone. SMB: 10MB/s FTP: 18MB/s. Why?

Hi,

I've been using OMV for about a year now using SMB shares.

When I transfer (large) files from my phone to the OMV SMB share (using File Manager+ on Android) , it's usually a stable 10-11MB/s (on 5.8GHz WiFi). I assumed that is my phone's or router's WiFi limit, because when I transfer files from my Windows laptop over ethernet, it's a stable 80MB/s.

Today I set up a FTP share to the same HDD and added this share to the same File Manager+ app. Now when I transfer the same large file, it's a stable 18MB/s. So I guess the WiFi was not the bottleneck. But then what is? Why are my file transfers much faster over FTP than over SMB? And where should I start to look for the culprit?

Thanks in advance!

I have done some cpu monitoring.

Indeed using FTP is hardly noticeable on the 4 efficiency cores. They are around 30%. Same as idle.

When using SMB, they average around 50-60%. But do spike to 100% once every 5 to 10s. Could that be the limiting factor even when the average load is much less than 100%?