Why am I getting the Apache2 Ubuntu Default Page instead of my own index.html page?

Try the following

Enable verbose logs

sudo nano /etc/apache2/apache2.conf

Locate the LogLevel variable, and update it from the default warn to info or debug. debug will produce the greatest amount of output.

# LogLevel: Control the number of messages logged to the error_log.
# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
# 
LogLevel debug

Restart Apache

sudo service apache2 restart

Apache includes a nice little syntax checking tool

apache2ctl -t

Checking Virtual Host Definitions

apache2ctl -S

For me, one of the suggestions from @Dan solved it.

sudo a2dissite 000-default.conf
service apache2 reload

Apparently the default site configuration was overriding my vhost configuration.

after installation index.html has higher priority that's why you still seeing default Ubuntu page check this folder var/www/html/ rename or remove this page simple as that