This release has passed my own experiments turning off and back on the Viessmann device.
MQTT counters get published (so you can view in HomeASsistant an error count going up while the Viessmann device is off) and then once the optolink is restored, everything goes back to normal. Hopefully this will be stable for a while!
What's Changed
Full Changelog: 1.2.6...1.2.7