In Apache 2.4 the old access authorisation syntax has been deprecated and replaced by a new system using Require.
What you want then is something like the following:
<Directory "/labs/Projects/Nebula/">
Options All
AllowOverride All
<RequireAny>
Require local
Require ip 192.168.1
</RequireAny>
</Directory>
This will allow connections that originate either from the local host or from ip addresses that start with "192.168.1".
There is also a new module available that makes Apache 2.4 recognise the old syntax if you don't want to update your configuration right away:
sudo a2enmod access_compat