I am following the steps I found for "Installing Cygwin and Starting the SSH Daemon" and in step 5.4.5 it has instructions to add the following line to the end of the C:\cygwin\etc\sshd_config file (only if installed version 1.7.31 or higher)

KexAlgorithms diffie-hellman-group-exchange-shal,diffie-hellman-group1-shal

What is the purpose of this?

I opened the file and did not find any Kex....text in the file.

Do I need this before I can proceed?

When I go to step 7 and run the command /usr/sbin/sshd I get the following results:

Duplicate