If your heat pump is successfully connected to the internet and to Havenwise, but you're still seeing an offline warning in the Havenwise app, there may not actually be a problem.
Havenwise runs a check roughly every 2 hours, so if internet connectivity has recently been restored, the error message should clear soon.
If you think the heat pump hasn't been offline recently, or the message isn't disappearing after some time, get in touch with the Havenwise team.