FTP speed very low

WD Legacy Products My Book Live
1

Hello.
English I own badly (from Russia). Help me

Problem:
MBL is connected to router ZyXel KEENETIC.
FTP is activated
Ports 20-21 on a router are redirected on MBL
FTP works, but speed of downloading the very low (10kB/s).

What there can be a problem?

2

I was helped by updating