Issues with indexing

Hi everyone!

Got an odd one. We used to be listed in google search results frequently, but all of a sudden it’s dropped off and can’t be indexed.

The only changes I can see being made to the site are a categories restructure and we enabled the data explorer plugin.

We’ve tried to add the sitemap to google, but it’s saying there’s a server error. However, we tested it against a third party validator which said it was valid.

We’ve also checked the robots.txt with googles tool, and it says we’re not blocking based on that.

So essentially, it’s saying they’re a valid format and not blocked by robots.txt - but still not indexing properly.

Any thoughts or suggestions would be mightily appreciated!