KcFErrorDomainCFNetwork error 303

I keep getting the above error on a specific website. I clear the affected cookie and it allows me to visit the site once and then the error comes up again.

I have spoken to the owner of the site and they keep saying to use another browser but I am running my business all on apple kit and want to keep it to Safari. I get the issue on my iPhone and iPad as well.

The link works without any issues in Chrome on all devices.

Appreciate any help

Regards

Jonathan