Hello, I am experiencing an issue where I am periodically observing the following notification in PLC Next Engineer software. The error message is: Arp.Device.Interface.EthernetLinkStateChanged This message is observed in the PLC Next Engineer software under Cockpit > Notifications. What causes this error message? Any suggestions on helping to troubleshoot this error message would be appreciated. Thank You Phillip C
Hi Phillip, These are not error messages, they are information messages in the form of “notifications”. Notifications that are automatically generated by the PLCnext Runtime are listed here: https://www.plcnext.help/te/Service_Components/Notifications/Notifications_by_Runtime.htm From the PLCnext Engineer help pages: 
That particular information message means that the state of one of the Ethernet ports changed, e.g. a cable was plugged or unplugged. ~ Martin.