matsuoshi

Maintenance Mode for Non-administrator login users. 
This plugin block access to Admin-page by Editor, Writer etc. 
Only Administrator can access the Admin-page while this plugin is active.
Meanwhile, this plugin doesn’t block visitors’ access to the site.

Admin Hot Maintenance Mode

Maintenance Mode for Non-administrator login users. Only Administrator can access the Admin-page.

Noor Alam

<a href="https://wphowto.net/simple-maintenance-plugin-wordpress-595" rel="nofollow ugc">Simple Maintenance</a> plugin can be easily installed to show a maintenance mode page. It allows you to maintain your site on the back end by displaying a temporary maintenance page on the front end.
The plugin does not require any additional configuration or setup. All you need to do is activate it and maintenance mode will be automatically enabled. It is very lightweight yet powerful. It uses the HTML5 layout which makes the maintenance mode page viewable from a mobile device.
<h4>Features</h4>
<ul>
<li>Clean HTML and CSS layout</li>
<li>Responsive maintenance mode page</li>
<li>No customizations required</li>
<li>Easier to manage as the maintenance mode can be turned on by activating the plugin</li>
<li>Notify the search engine crawler that the site is down for a limited period of time</li>
</ul>
For more information please check the <a href="https://wphowto.net/simple-maintenance-plugin-wordpress-595" rel="nofollow ugc">WordPress Maintenance Mode Plugin</a> documentation page

Simple Maintenance

Really simple and to the point. Exactly what I was looking for. I just had to modify the message and the styles a bit.

Great plugin

Display a simple maintenance mode page while your site is undergoing scheduled maintenance

Admin Hot Maintenance Mode vs Simple Maintenance