Guys (@Cplant@michab), it seems the latest test version 2.4.42 (published through Test Flight) solves the problem, the sitemap started to load also through internet. There is an auth error first, but then it loads. In the version description, they mention “Fixed connection to myopenhab.org”.
@abal - I tested it when i was mobile and it worked. First it show a connection error - but when pressing “Refresh” it works. Great so far. Thx to the product team.