OPC UA server has happily been using IP address for a Kepware connection.
Server is 7.6.3-rc2
For some reason IP is now being replacing by hostname and cannot get name resolution as there is no active DNS on this network segment currently.
The forum
viewtopic.php?f=70&t=10376&p=37038&hilit=host+override#p37038
Gives us a workaround.
If you however use the Host Override one gets a NullPointer Fault for any text (host or IP) entered.