During the last maintenance where vox ran into some issues it appears that the ability to downgrade php was revoked, I talked to another admin about it and hopefully that will be added in back later today/tonight. For now you will get that forbidden error if you have downgraded the version in your .htaccess. You can get rid of the forbidden error by adding #at the start of the line for the downgrade in .htaccess.
Since I assume you did the downgrade for a reason that could bring back other issues you had though, but to show the visitors a better view you could revoke the downgrade and for instance put a blank index.html or a simple one that says maintenance or something similar.