By default, when you enable the Under Construction Mode, all pages on your site will be affected by it. So, no matter which page is loaded, the under construction page will be displayed instead.
If you want to include only some pages or exclude a few of them from the Under Construction Mode, you can set URL based rules.
Settings -> UnderConstruction -> Access -> Access Rules
Use this option to set per URL rules and lock down the entire site except for the selected pages, or lock down just some pages and leave all others accessible to visitors. If the second option is used all other access rules still apply.
Enter one URL per line. Start and end URLs with a forward slash (/). For example /my-page/ or /tag/featured/.
Customers who purchased and have a valid PRO license - contact our support via the contact for built into the plugin or use the general contact form. If you're using the later method please include your license key in the message or contact us via the email address used when purchasing. This speeds things along.
Using the free version? We have you covered too. Head over to the forums. First look at older threads and if you don't find anything useful open a new thread. Support is community-powered so it can take some time to get an answer. If you need premium support this second - upgrade to PRO.