Thanks for your reply .
Right after the message, I performed the same process again, and ... crashed everything.
I had to re-install both sites.
So, after around 10 attempts, I came to the following conclusion :
- with aws lightsail, when using wordpress multisite, it's ok to create one main site and one subdomain site on the same instance; sharing the same IP address.
- But with this configuration, when it comes to add a ssl certificate with the
sudo /opt/bitnami/bncert-tool command, it seems that it can not be distributed to all sites (main + subdomain). It will be either one or the other (in the best case scenario, for it could possibly break down both sites).
It's very likely that I proceeded the wrong way or missed something, for I am totally new to this topic.
But, just to stay on the safe side (and save hours of anxiety), I decided to :
- create a new instance for the subdomain site, and grant it with a specific IP address
- associate a certificate for each site (one at a time, and not all in one go).
All the best,