MAC Error

Remote Server Information
Remote SSH Server version: SSH2
Remote Operating System distribution name and architecture: APC Network Management Card (firmware based)
What kind of access do you have?: Full physical and software access
Does Putty/WinSCP work?: Yes

Local Machine Information
Operating System: Windows 10 1809
.NET Framework versions installed: 1.0.3705, 1.1.4322, 2.0.50727, 3.0, 3.5, 4.0.30319

Project information
What is your target framework and architecture: x64 .NET 4.6.1
Is your project multi-threaded/complex: Initially found bug in asp.NET app, vested/debugged in simple C# console app.

Source Code
Sample Code: https://gist.github.com/vrelk/b04c27de3c0203d156511f4e41e30a33
Exceptions and Stack Trace/Call Stack: https://gist.github.com/vrelk/bc135745dd2eb3e34ecc15c0a514b1aa

File transfer related: No

Transfer over LAN or Internet?: LAN
File size in bytes: N/A
Uploading or Downloading? N/A
Does remote server have enough space to store the file? N/A
Do you have access to the file being uploaded or downloaded? N/A

Associated Putty connection: https://i.imgur.com/JG0DDZ8.png

Note: These cards are very primitive, and don't run an off-the-shelf SSH server, which is probably part of the issue, but putty works without an issue. If you want to take a stab at it, I have more cards, I might be able to get one on a public IP for you to mess around with.

Start with the linked sample code and exception stack trace, then reproduce the connection against an APC Network Management Card using the reported .NET and Windows environment. Compare the failing SSH.NET behavior with the working PuTTY connection; done means the MAC error has a confirmed cause and the compatibility work has a clearly verified result.