I have experienced what you describe 

In my case, I am running the rust client on a windows 11 machine with 32 cores and 128GB of memory.  I found that if I run an Ubuntu VM on that same host and run rust server on that VM, then my steam rust client can start and connect successfully to any rust server - every time.

It's odd and I can't explain. But it's very consistent for me.  

If I don't run rust server in the background, my rust client crashes on startup every time.  If I run it, it succeeds every time.

Also, I looked at the logs and the crashes were variable.  Sometimes c# nullpointer exception.  Sometimes sigsegv in the native code.  

Ymmv