After updating to stunnel-5.43.1, stunnel no longer responds in any way, no error messages and any indication of an attempted connection. I tried it both on a cubie truck and a raspberry pi 2. Previously, these systems had been running for years. Part of the update including systemd-235.38-2 which had some new firewall warnings. Netstat shows stunnel listening on the ports that are specified in the configuration file.
Any hints about where to go would be appreciated.