I have Ubuntu 16.4 on a DigitalOcean droplet with Serverpilot Apache/Nginx. I have a number of serverpilot apps differentiated by folders eg apps/appname1/public and apps/appname2/public.
Having installed several certificates before on other droplets it seems that the whole droplet/server requires SSL for any access. So appname1 might have a certificate but if appname2 does not despite being in a separate folder still gets a severe warning about being insecure. All the apps have the same IP address.
So in short, if one app has SSL must they all (if sharing the same IP)?