Cygwin sshd broken by seemingly trivial network change

[Charles Russell]

On 12/16/2020 9:37 AM, worsafe@bellsouth.net wrote:
 > While installing a new router, I changed my local network from
 > 192.168.4.* to 192.168.50.*. This seems to have broken Cygwin sshd on
 > both of my remote computers, but only for Cygwin; sshd works fine if I
 > boot the remote computer from a linux thumb drive. I have noticed no
 > other problems with the new network configuration.

 > -------
 > nmap shows port 22 open on the remote server:
 > nmap -p22 $ASUS12
 > Nmap scan report for asus12 (192.168.50.105)
 > Host is up (0.13s latency).
 > PORT STATE SERVICE
 > 22/tcp filtered ssh
 > ----------
The last line was a giveaway.  The problem is with the Windows firewall. 
However, I have found no remedy apart from totally disabling the 
firewall. The old settings no longer work: sshd is enabled for both 
private and public networks, but the firewall is still blocking access.