Thank you for the fast reply, I guess this should work for the Xpenology if it would not be able to connect to the internet.
In my case it was the PC not able to connect to the internet.
I've fixed it now, it seemed like I've made it too difficult for myself. I've setup alle these settings in DSM, where i should have let it on DHCP (client) mode and set my PC IP hard in the same range as the Mellanox in the XPenology.
Everything is working now with faster speed between PC and Xpenology