Server security settings

I’m having issues with communication with Printspace who fulfil all my online printing orders.
They have said the following but not sure how to do this…can anyone advise please?

“I’d also check your server security settings. If you use a 3rd party such as Cloudflare for security, it is likely this service is blocking the communication from our server via their bot detection service or something similar. You can make an exception for our server which should allow the connection to be made. Our IP is:”

An IP Access rule should make that exception:

You can also try looking through your Firewall Events Activity Log to find out what may be blocking those requests.