Finalizer will not run in .Net Core builds, becareful and remember to manually call them.

[jianmingyong]

Ever since .Net Core changed the behavior of finalizer, it will never release the ports on time. To be safe, users have to call NatDiscoverer.ReleaseSessionMappings(); manually to ensure it is properly released.

Sadly this break the last failover ditch effort some people may expect it to work. Of course there is still a workaround with this using:
AppDomain.CurrentDomain.ProcessExit event. Only use this workaround on .Net Core builds if you want to ensure it release the session mappings if people click the X button.

[lontivero]

Yes, you are right, thank you.

[lontivero]

This is important now because I will upgrade the library to netstandard2.0 soon.