C# System.Random guarantee same results

I wanted to work with System.Random once again but this time I really need the same results when using the same seed. The official documentation mentiones that the results may varry between different versions of .NET.
This has to work on .NET Core and has to give the same results on Windows aswell as Debian indipentently of the used version of .NET.
I know there is/are some cryptographic PRNG(s) in .NET but I need less security but nore effective speed when rolling the numbers.
How safe is it to use System.Random when it has to guaranteed give the same results?
Is there some class build into .NET which guarantees not to change it's PRNG algorithm?
Also speed is more important then real randomness but it shouldn't return 4 every time ;)
Thank you really much!