Man am I grateful for your post!
This just happened to me and I thought I was crazy.
I want my LEMP server for joomla so I needed extra php modules.
My NGINX broke after installing the php modules and rebooting. Eventually I traced it back to a port 80 conflict with.... apache2!!!
I was incredulous. I had no idea why apache2 was on my server or how it had got there.
I thought I must have (???) installed it or activated it myself but had no idea how…
All I had done was run the following command and reboot and NGINX stopped working:
sudo apt install php7.2-mbstring php7.2-xmlrpc php7.2-soap php7.2-xml php7.2-intl php7.2-zip php7.2-gd
So I created a new LEMP droplet to install them and reboot one by one.
php7.2-gd was the problem!
But at that point I realized that it wasn’t me. Apache2 was already on the server to begin with!
And somehow installing php7.2-gd makes apache2 take over on port 80.
So, as you said, this problem has just made a beginner go crazy for hours. I wish someone could explain why apache2 is even on the server. I’m scared of uninstalling it.
Could removing apache2 cause some kind of security issue? I’ve already been hacked 3 times over the years.