How does this plugin affect search engine rankings?

From the plugin’s perspective it’s follow all guidelines by Google when a downtime occurs. Here’s more on the subject https://googlewebmastercentral.blogspot.com/2011/01/how-to-deal-with-planned-site-downtime.html

https://www.seomoz.org/blog/how-to-handle-downtime-during-site-maintenance

The plugins returns a 503 and retry header. I think the fact that your had your site down for an excessive amount of time is the reason you lost your index. The 503 header stop Google from indexing the temporary state of the site.

You’ll probably regain once Google re-crawls the site. You’ll have to wait for that to occur now.

Here’s some more on the topic, it does appear Google will penalize for excessive downtime. But ranking recovered once his site was back up.

https://productforums.google.com/forum/#!msg/webmasters/CNNJ35Bb98Y/5YNpl-5DEC8J

John – thanks for the swift response and explanation. I’m keeping my fingers crossed that my Google indexing/ranking improves!

In hindsight, I guess I should have managed my maintenance mode better in order to keep my downtime to a minimum. That said, I am a business manager first and foremost (as opposed to a web developer or systems administrator) and didn’t have either the time or level of knowledge I would have liked.

May I suggest adding some notes to the plugin so that other people who are of a similar ‘ilk’ to myself (i.e. not especially technical) are aware of the dangers of leaving their website in maintenance mode for too long.

Many thanks.