https Webfig works just one session only, then stops/crashes...
...until one logs in via for example ssh and restarts the service manually by issuing this:
/ip service enable www-ssl

I don't know whether the above command is really the correct one for starting a service, but here it works.

Btw, how in the CLI (via ssh etc.) can one check the status of the www-ssl service, or of any of the services, ie. whether it is actually running or not?

PS: the www service (http) works fine, it does not crash, but of course http is insecure as it does not use any encryption... --> MITM/A possible...