I just started with pi3 and all OS around I want on this exactly your way, nextcloud. after all, is was work but I need put trusted side – my ddns for access outside, and also edit ports, my 80 and 443 is using by different accessories.
before I use VM and there ubuntu and owncloud. there I was all setup do in terminal. but there is complete different.
could be easily but not for me you got port forward problem is when I put my new port 84 is still there port 80 is well that I need take it out.
is any possible change to change everything in terminal – putty -ssh ??
even if your ports 80/443 aren’t really closed but occupied with something else…