Unable to load DLL: The specified network name is no longer available

for some reasons I must have dll in not in same folder where main executable lives. I use the method described here https://stackoverflow.com/a/2864714/5492345. My code looks like this:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.InteropServices;

namespace testnetwork
{
class Program
{
    [DllImport("SomeLibrary.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, SetLastError = true)]
    public static extern int SomeMethod([MarshalAs(UnmanagedType.AnsiBStr)] string someInput);

    static void Main(string[] args)
    {
        string CurrentPath = Uri.UnescapeDataString(new Uri(Path.GetDirectoryName(Assembly.GetExecutingAssembly().CodeBase)).AbsolutePath);
        var paths = new List<string>
        {
            CurrentPath + "/Folder1",
            //CurrentPath + "/Folder2",
        };

        AddEnvironmentPaths(paths);

        SomeMethod("myinput");
    }

    static void AddEnvironmentPaths(IEnumerable<string> paths)
    {
        var path = new[] { Environment.GetEnvironmentVariable("PATH") ?? string.Empty };
        string newPath = string.Join(Path.PathSeparator.ToString(), path.Concat(paths));
        Environment.SetEnvironmentVariable("PATH", newPath);
    }
}
}

Everything is working fine until I have internet connection. When there is no network connection I get an error

An unhandled exception of type 'System.DllNotFoundException' occurred in testnetwork.exe Additional information: Unable to load DLL 'SomeLibrary.dll': The specified network name is no longer available. (Exception from HRESULT: 0x80070040)

Seems like DllImport works differently when PC is disconnected from network? In my %PATH% variable there is no any UNC paths.