Just an additional update:
I have checked using a few different laptops at the same time – no issue.
The issue seems to happen when a device is accessing the mobile version of the site (tested 2 different iphones). This means the desktop version gets the err_connection_timed_out message. This happens when the mobile is accessing the ‘free tools’ section on the site.
My hosting is with godaddy, if that makes any difference.
I’m really stumped here.