I want to preface my problem by stating that I tried everything on this post:
Unity Scripts edited in Visual studio don't provide autocomplete
And that auto-completion work for things like "Vector3.up", but I don't have recommendation when I want to write, for example: private void OnTriggerEnter(), I write until "OnTri" and nothing pops up as it should.
Now, I use Unity 2017.3f1 for the purpose of a lesson, and Visual Studio Community 2022, with Unity tools installed, and vs 2022 as my default engine on Unity external tools.
I used to have my Unity version set on the most recent build before I downgraded my whole project to the version I use now, which triggered visual studio to make me download the target sdk ( .NET 4.6 ) which I did.
My other project ( latest version of Unity ) have IntelliSense and auto-completion ( related to Unity stuff ) who works just fine, so it must come from my Unity 2017 Project, but I can't figure a way to make IntelliSense work completely with the script of this project.
I don't know if this will help finding the problem, but when I right click I can't even use Unity short messages, the option doesn't show (on my 2017 project, works fine with most recent project).
I use the same SDK as the one in Unity Player Configuration... (which vs asked me to install at the launch anyway).
I reimported everything, did everything in the post I linked above...
I'm lost.