If the WAP is not in the list of supported Unleashed products, it won't work. However, H510 is in the list.
It should be a very little difference in price for H510, try exchanging it. Also, for you use Mesh, keep in mind that it creates a link on 5Ghz, meaning your signal has to be good enough for mesh link to form.
H500 is not supported under Unleashed portfolio. No, H510 Unleashed code is not compatible with H500 AP.
Now let me help you with a solution to achieve your goal.
You mentioned that you have R500s throughout your school. Are these getting managed by ZoneDirector or SmartZone controllers? If so, you can enable "mesh" on the controller which will allow your H500 to become a mesh AP. Once H500 becomes a mesh AP, as you said, you can then plug-in your printers/desktop to those LAN ports.
Hi Nat, we have no controller they are just linked, when one goes down one of the other 8 just takes over as master. Not sure what this is classed as? I have the option when I login to the r500 admin page to enable mesh, so would this do it? Thanks for your help
Sounds like you are running Unleashed (controller-less) solution already in your network. Is such instance, you would need Unleashed H510 AP (not H500) to add to your network. Unleashed H510 supports mesh.
To enable, yes, you have to do it under 'Admin & Services -> Mesh'.