As it turns out my host needed me to add the IP to my /etc/hosts file and point to my domain, as I was using the test url given to me when I setup the account.
So on my shared hosting I had a test url of 101.111.111.12/~testing which works fine, but a recent update to mod_security causes issues if you use this URL and post an iframe into a custom text field. It triggers a 403 error and some sort of CORS issue arrises.
I’m really clueless with sysadmin so a quick call to my host was able to sort this out for me.
Moral of the story if setting up a testing url with a shared host, add that IP to your local /etc/hosts file to get rid of any headaches and that will make the site behave as expected, for example if you setup a new account for testing.com and get given a temporary url of 100.100.11.11/~testing edit your /etc/hosts file to have 100.100.11.11 http://www.testing.com testing.com
I hope this helps someone else who isn’t great with sysadmin like me.
