To reproduce:

• Start a 4.4 server (any topology, single is fine)
• Connect
• Stop the server

Observe flood of:

W, [2020-11-02T22:53:19.919183 #21156]  WARN -- : MONGODB | Error running awaited ismaster on localhost:14400: Mongo::Error::SocketError: Errno::ECONNREFUSED: Connection refused - connect(2) for 127.0.0.1:14400 (for 127.0.0.1:14400 (no TLS)) (on localhost:14400)

... which stops once the server is restarted.

Awaited ismasters should only be performed on known servers, this server should be unknown while it's not running.