PLC Ethernet comm Error

Hello all,

I'm having problem with our FX5U Ethernet connection. We're having 3 identical PLC which connected through LAN cables. PLC 1 (Unpassive-TCP), PLC 2 (Active -Active -TCP), PLC 3 (Unpassive -TCP). I'm trying to change PLC 1 ethernet connection from Unpassive to SLMP, but it's not working. Later I reload backup program fully to PLC 1. Unfortunately connection from PLC1 to PLC 2 was giving error after re loading. While from PLC2 to PLC3 without any problem. Program verification between Backup and PLC give me Device Memory error. When I test PLC function all working (all equipment running), only communication from PLC 1 to PLC 2 can't estabilished. Any suggestion please ?

Thank you