The following example is using a local network (IPv4) and a DirectAccess (IPv6) network. On the client-side machine (where ArcGIS Desktop resides), update the ESRI LICENSE_SERVER registry key in the registry using Windows Regedit to add the second IPv6 address of a License Manager assuming if you have IPv4 connection. It’s very Important that before making any modifications to the registry, back up the registry for restoration in case problems occur.*** If you require a connection for both protocols to a License Manager, a workaround is to configure the registry. However, only if the machine and operating system environment support IPv6. Please note that the IPv6 is supported for the License Manager.

internal network) or to IPv6, for example MS DirectAccess, that uses IPv6 connections not to both protocols. The connection is usually set to be IPv4 (e.g. Are you having trouble connecting to the ArcGIS License Manager (LM) when using IPv4 and IPv6 connections? When using Dual-IP stacks, your computers and other devices can run both protocols however there can be issues when connecting to an ArcGIS License Manager.

Arcgis license manager 10.3