.NET 4.7 and license problem

We have a customer that is running Sitefinity 6.0.4200. They have license for several domains, all are using the same top domain of type xxxx.company.com where xxxx are what differs. We started to move one of the web sites to a new server (all will be moved to  this server but we want to do it step by step), a windows server 2016 and we started to get problems with that it won't remember the license.

I thought it hade to do with having one web using a different ip than the rest but after searching I found out that this is a problem with .NET 4.7 and the version of Sitefinity that is used.  I testade to set the sites idle time to 1 minut and after 1 minut it asked for a license again. Then I set it to never idle and not recycle and now it doesn't ask for the license until I force a recycle or restarts the web itself.

I wanted to recreate the problem so I installed a virtual Windows Server 2016 and installed .NET 4.7 on it. The strange thing is that I don't get the same problem here.  Could be that it is the case because it's not a public site?

So my question is if the problem probably is becuase of .NET 4.7 or if we are getting the problem because we are moving the web to another ip number and still having the other domains on the old ip? Or perhaps both?