sshd refuses connections until I restart the daemon

[Patrick McMunn]

I sometimes access my FreeBSD 11.1-RELEASE-p9 box from my laptop via ssh.
Sometimes I can connect, but sometimes I get the message "ssh: connect to
host 192.168.0.71 port 22: Connection refused". But if I walk over to the
computer and manually restart the sshd daemon, I can then go back to my
laptop and successfully ssh into the FreeBSD box. Why would it stop
accepting ssh connections until restarting the daemon, and how can I fix
this from recurring?

-- 
Patrick McMunn