ZF7055 One port connected, two ports UP

[victor_samuel_a]

Something strange with my zf7055. 

I have PORT 5 (POE connected of the ZF7055 to the POE switch. 
However, in the device status, PORT 4 shows as UP, but there is nothing connected to PORT 4:
Port Interface 802.1X Logical Link Physical Link Label

0     eth1       None    Down          Down               LAN1
1     eth2       None    Down          Down               LAN2
2     eth3       None    Down          Down               LAN3
3     eth4       None    Up            Up 10Mbps full     LAN4
4     eth0       None    Up            Up 100Mbps full    POE IN, LAN5/UPLINK

Then, on another ZF7055 I have PORT 5 (again, POE) connected to the POE switch, but PORT 3 shows as UP:
Port Interface 802.1X Logical Link Physical Link Label

0     eth1       None    Down          Down               LAN1
1     eth2       None    Down          Down               LAN2
2     eth3       None    Up            Up 100Mbps full    LAN3
3     eth4       None    Down          Down               LAN4
4     eth0       None    Up            Up 100Mbps full    POE IN, LAN5/UPLINK

Both are running on 100.1.0.0.194 firmware version. 

Can anyone help me find out what is wrong?

Any help will be much appreciated.