Samba: upload is stuttering and crashing

[xXSkyWalkerXx1]

I have installed Samba on my Raspberry Pi 4 under Arch Linux. If I upload something from my windows laptop to my pi server (in more detail: to my WD harddrive mounted as NTFS, connected with the Pi) via smb the upload is slow (2-5Mb/s), stuttering and then the smb-service crashs randomly. After I reboot my Pi it works again for a short time, even the upload speed is better, but then there is the same issue.

- samba config file (smb.conf) has nothing set which takes an effect on the connection
- dmesg: 'Out of memory: killed process (smbd) toal-vm: 88668kb, anon-rss: 2176kb, file-rss:17152kb, shmem-rss: 0kb, ...', the same with sshd and so on
- memory in use during upload, using 'top': ~400/7100

It seems that the last months this issue became more and more.

Anyone else any idea??
Thanks,-