Wampserver - accessing my website from an external device redirects to localhost

I am trying to put my Wampserver website "online". When I try to access my Wampserver website from a different device, the device will redirect to localhost. For example: My computer running Wampserver has a public IP Address of xx.xxx.xx.xxx. When I type "http://xx.xxx.xx.xxx/site1/" on my phone, the phone's browser will redirect to "localhost/site1/", which (obviously) fails to connect.  

Computer running Wampserver/Wampserver/PHP/Apache details:

Windows 10  
Wampserver 3.2.3  
phpMyAdmin 5.0.2  
Adminer 4.7.7  
Apache 2.4.46   
PHP 7.4.9   
MySQL 5.7.31

The website I want to put online is inside a folder named "site1" and this is my apache vhosts.conf: (Computer's private IP is 192.168.254.13):

# Virtual Hosts
#
<VirtualHost *:80>
  ServerName localhost
  ServerAlias localhost
  ErrorLog "${INSTALL_DIR}/errors.log"
  DocumentRoot "${INSTALL_DIR}/www"
  <Directory "${INSTALL_DIR}/www/">
    Options +Indexes +Includes +FollowSymLinks +MultiViews
    AllowOverride All
    Require local
  </Directory>
</VirtualHost>


#
<VirtualHost *:80>
    ServerName site1
    ServerAlias 192.168.254.13
    DocumentRoot "c:/wamp64/www/site1"
    <Directory  "c:/wamp64/www/site1/">
        Options +Indexes +Includes +FollowSymLinks +MultiViews
        AllowOverride All
        Require all granted
    </Directory>
</VirtualHost>

Windows hosts file:

127.0.0.1   localhost
127.0.0.1   site1  

My port is forwarded properly. If I set the localhost vhost to "Require all granted" instead of "Require local", I am able to see Wampserver's config page from my phone by typing in my computer's public IP address.  

Any advice to point me in the right direction would be greatly appreciated.

When I try to access my Wampserver website from a different device, the device will redirect to localhost.

One issue here is that Apache has a "default" virtual host (the first host it loads). In this case, that is your localhost entry. This host is returned when no other virtual hosts match a request (in your case, when accessing Apache via an IP address).

As a side note, I don't believe ServerAlias can be used for IPs. As far as I am aware, it is for name-based virtual hosts only.