The table below (screenshot and link below) is pretty clear about version compatibility for the Utility Network.
My questions is if it is safe to use the UN with a higher version of Pro once created. E.g. if I am at enterprise v.10.8.1 and create a v4 UN with Pro v2.6, but then have user publishing and interacting with the UN at Pro v2.7, will they run into issues? Should all users and admin stick with Pro v2.6 and only upgrade to v2.7 when the enterprise goes to 10.9? Thoughts or experience with this greatly appreciated.
In my experience, it was OK if Pro 2.7 was used to interact with a v4UN created with Pro 2.6 at 10.8.1. This would included editing, validating etc. For admin purposes, disabling network topology, adding rules etc. I have kept that version of Pro at 2.6. This is just MY experience others may have differing views or different experiences. I would love to hear what others think....
Good morning @LorenMueller
Great question! There should not be any issues encountered using a later ArcGIS Pro client (such as 2.7) to interact and work with an earlier version of the utility network (such as UN v3). To put it another way, while you can use a newer client and server version to take advantage of new functionality, there is no obligation to upgrade the utility network's version to be "current" with the client or server release. While some capabilities and functionality may only be available with later versions of the utility network (such as working with nonspatial objects), this does not prevent the client from working with the earlier version.
The compatibility chart you referenced is primarily concerned with the version of the utility network created through the combination of client and enterprise during creation or upgrade. The version of ArcGIS Pro and ArcGIS Enterprise determines the Utility Network Version value when creating or upgrading a utility network.
Earlier ArcGIS Pro releases cannot open utility network datasets that participate in newer functionality. For example, you'd encounter issues if you tried to use ArcGIS Pro 2.4 and ArcGIS Enterprise 10.6.1 for sharing a utility network that has a Utility Network Version value of 4.
Hope this helps to clarify.