ODROID HC2 (Showing 100mb Ethernet on Router)

Hi, I'm very very new to OMV.

I have just purchase and installed a Odroid HC2 ( which has gigabit ethernet).

The problem I have I seem to have transfer speeds of about 8-10mb, I have checked my connection speed on my modem/router and it is showing as a 100mb Ethernet connection?

Any advice/ help would be much appreciated!!!

Since posting I have checked my 7mt Lan Cable and discovered it's CAT 5.... not 5E.

Swapped for 5E cable far better transfer rates. Many Thanks.