Hi Gerard,
I have no clue about Node-RED, but do you see anything in your logs related to Somfy? You could give https://github.com/imicknl/ha-tahoma a try as well. This integration uses the tahomalink.com server which could be more reliable…
See Tahoma Integration Refactored - Share your Projects! / Custom Components - Home Assistant Community (home-assistant.io)
and
Somfy Tahoma Official API - Feature Requests - Home Assistant Community (home-assistant.io)
@tetienne any idea?