@whitequark also, in the webhook, "test delivery" now gives me a 200 response.
and... (holding my breath): sub1.swiss-soccer.net displays....
404 not found.
Ah well, at least I'm closer. Let me see what's going on.
(When this is all done, I want to write up what worked for me, and if I may, share it with you and anyone else in the same boat.)