This is the error that I get when I try to access the PC from my phone.
in your apache.conf file
<Directory "/var/www/html/yourwebroot"> AllowOverride All Allow from all Require all granted </Directory>
and restart your apache2 server
The access control configuration changed in 2.4, and old configurations aren’t compatible without some changes. See here.
If your old config was Allow from all (no IP addresses blocked from accessing the service), then Require all granted is the new functional equivilent.