Thanks for the responses so far. Here is what we have tried:
- Adding port name to the end of the domain alias
- Checking CF settings
- Purging CF cache
- Setting visitor culture to the same as the main domain (it was previously set to automatic)
- Checked proxy, internal network and firewall settings
None of the above has resolved the issue. I am now just waiting on a response from my hosting team to see if the bindings set in the same way on the IIS for all the domain names.
If we wanted to narrow down whether this is a CF or Kentico issue, how do we bypass CF? Sorry, this must seem v basic to some but I am completely outside of my comfort zone on this one!!