WDMyCloud cifs copy speed slow with linux

Hi,

I have WDMyCloud NAS with latest firmware.
I have 2 windows pc with gigabit ethernet. These computers copy from NAS over 80-90MB/s
I have 2 linux pc with gigabit ethernet, and when i mount my NAS, and copy to /dev/null the speed is between 4-41MB/s and with nfs 69MB/s :

MiniMX:~ # mount -t nfs 192.168.1.3:/nfs/Public /storage/test
MiniMX:~ # dd if=/storage/test/lib.img of=/dev/null bs=1M
548+0 records in
548+0 records out
574619648 bytes (548.0MB) copied, 7.928456 seconds, 69.1MB/s
MiniMX:~ # umount /storage/test
MiniMX:~ # mount -t cifs -o username=admin //192.168.1.3/Public /storage/test
MiniMX:~ # dd if=/storage/test/lib.img of=/dev/null bs=1M
548+0 records in
548+0 records out
574619648 bytes (548.0MB) copied, 13.124313 seconds, 41.8MB/s
MiniMX:~ # umount /storage/test
MiniMX:~ # mount -t cifs -o username=admin,rsize=131068 //192.168.1.3/Public /st
orage/test
MiniMX:~ # dd if=/storage/test/lib.img of=/dev/null bs=1M
548+0 records in
548+0 records out
574619648 bytes (548.0MB) copied, 107.169482 seconds, 5.1MB/s
MiniMX:~ # umount /storage/test
MiniMX:~ # mount -t cifs -o username=admin,rsize=8192,wsize=8192 //192.168.1.3/P
ublic /storage/test
MiniMX:~ # dd if=/storage/test/lib.img of=/dev/null bs=1M
548+0 records in
548+0 records out
574619648 bytes (548.0MB) copied, 70.516801 seconds, 7.8MB/s
MiniMX:~ # umount /storage/test
MiniMX:~ # mount -t cifs -o username=admin //192.168.1.3/Public /storage/test
MiniMX:~ # dd if=/storage/test/lib.img of=/dev/null bs=1M
548+0 records in
548+0 records out
574619648 bytes (548.0MB) copied, 13.477272 seconds, 40.7MB/s

How can i reach that speed with linux, what i can use with windows?
I have latest firmware.

Since the unit appears to be working as intended in Windows then it could be a system configuration issue. Hopefully an experienced Linux user will be able to assist.

No idea why CIFS copy speed so low?