C# System.Random with same results [closed]

I wanted to work with System.Random once again but this time I really need the same results when using the same seed.
This has to work on .NET Core and give the same results on Windows aswell as Debian.
How safe is it to use System.Random when it has guaranteed to give the same results?
If not, which PRNG can/should I use?
Personally I would prefer something build into .NET Core (maybe something from a crypto lib?) or if there isn't anything thats safe to use in .NET, I would prefer a simple-to-add .dll (.NET Core compatible) over a nuget package.
Also speed is more important then real randomness but it should do then return 4 every time ;)
Thank you really much!