Not sure how I can check whether my current NethServer is using TLS-SNI-01 Validation Support and how to change to the “TLS-ALPN-01” method …
Appreciate assistance…
If you used the server manager to get your cert, it shouldn’t be using this validation method; it’d be using http-01 instead. To confirm, you can look in /etc/letsencrypt/renewal/*.conf for the renewal configuration file for your domain. The line that says pref_challs = will specify which challenge is being used–most likely, it will say http-01.