Thanks for your reaction => I got it partially working (adapted the entries in configuration.yaml according to the example in the paged you referred to + configured the internal and external url ).
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I now have a secure connection from outside my local network, I have “the lock”
But … I am no longer able to access HA from inside my local network.
I always used “ip:portnumber” (http://192.xxx.xxx.xx:8123), but that isn’t working anymore, I get the message “This page isn’t working, 192.xxx.xxx.xx didn’t send any data”.