Your comments

As a quick fix I am subscribing to the current time of the server which updates every second.

And this does keep the connection alive.

But this feels more like a dirty fix instead of a solution to the problem.

I bought Game4Automation Digital Twin Professional 2020 2020.15 back in 2019.

I now realize that the OPCUA4Unity is build into the package and I just downloaded the latest version of this deprecated package.

In this post I saw that you have a version that supports multiple nodes per subscription. Which is exactly what I need.

https://forum.realvirtual.io/communities/1/topics/158-opcua4unity-adding-monitored-items-to-subscription

However when I download this version all the dll files for OPCUA4Unity seem to be missing:

error CS0006: Metadata file 'Assets/OPCUA4Unity/private/BouncyCastle.Crypto.dll' could not be found
error CS0006: Metadata file 'Assets/OPCUA4Unity/private/Opc.UaFx.Client.dll' could not be found
error CS0006: Metadata file 'Assets/OPCUA4Unity/private/OPCUA4Unity.dll' could not be found
error CS0006: Metadata file 'Assets/OPCUA4Unity/private/System.Private.ServiceModel.dll' could not be found
error CS0006: Metadata file 'Assets/OPCUA4Unity/private/System.Reflection.DispatchProxy.dll' could not be found
error CS0006: Metadata file 'Assets/OPCUA4Unity/private/System.ServiceModel.Primitives.dll' could not be found

Is there a way I could get these dll's? This way I can implement the multiple nodes per connection or is this not implemented in this version also?

version is game4automation-OPCUA4Unity-1.026

I am using Unity version 2020.3.41f, version 1.0.0.0 of OPCUA4Unity.dll and version 2.7.1.2 of Opc.UaFx.Client