Lan speed

Hi, I have problem with lan speed. I have transfer about 25MB/s in 1Gb lan. According to specification my NAS (WD My Cloud) should has Gigabit Ethernet port. I found that 100Mb connection has a green light and 1Gb has amber light. I discovered that my computer has amber light but NAS has green one.
I made also crossed cabel and connect computer and NAS without any switches, my speed was a lite bit more about 30MB/s.
Can some help me, maybe I should change something in OMV 2.1.17.

Thanks for help.

Hi, command: ethtool eth0 give results:

Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: external
Auto-negotiation: on
Current message level: 0x00000036 (54)
probe link ifdown ifup
Link detected: yes

yes, OMV is installed on WD My Cloud 2TB, inside is disk: 2.0 TB WD RED (WD20EFRX).

I put to SMB etra option: max protocol = SMB2
nothing changed still uplod speed to NAS about 25MB/s, download speed about 38-40MB/s

after that I found next solution and put:

max protocol = SMB2
max xmit = 65535
socket options = TCP_NODELAY IPTOS_LOWDELAY SO_SNDBUF=65535 SO_RCVBUF=65535
read raw = yes
write raw = yes
max connections = 65535
max open files = 65535

also nothing changed still the same speed.

I've inastalled Fox_exe version 1.16a and I've updadted to 2.1.17.

Do you know how could I change kernel from 4kb to 64kb.
Thanks