Intermitting 404 Errors

Good morning,

I used the duplicator plugin to move an existing site into a demo area to carry out some updates and redesign work. Duplicating the site across to another server went fine but I am now faced with random 403 Forbidden Errors. The site works fine for a few hours and then all of a sudden it stops and I get a 403 message.

I have checked all the permissions and they are fine so I am not sure what is causing this issue.

Any advice or guidance would be greatly appreciated.

The page I need help with: [log in to see the link]