Communication problem

Can't connect to Multisizer 4 via IP protocol.

Tried:

• Checked cable (tried another cable)
• Checked PC NIC IP config
• Checked software target IP (192.168.255.2)
• Tried another computer with same software settings and same NIC IP settings (192.168.255.1)
• Tried tcpdump (packet sniffing) on eth port from the PC and not receiving a single IP packet. 
• Tried router with DHCP server between computer and Multisizer: no DHCP lease given to Multisizer even after several reboots
• Tried APIPA IP in case the Multisizer falls on APIPA: nothing

Anyone had same issue? Beckman Coulter tech crew offers me to buy NS486 Controller or Main control board. I hope someone had the same issue here and would tell me it was solved by replacing which part.