After a bounce of IP addresses this morning, the server is being bombarded with requests to port 11326 from all over (192 different IP addresses and counting). 4616 requests in two and a half hours. A google search on what might be lurking at port 11326 doesn't reveal the problem, though there is the possibility it is associated with the OpenPBX/CallWeaver program.

UPDATE: 3:45pm
6 hours have passed since the initial post and it's up to 703 IP addresses making 12726 requests.

UPDATE 2: 5:45pm
Finally set up a netcat on the port to do ...

My apologies for any and all connection problems. The domain is currently experiencing hosting issues with some configuration or directive having changed upstream.

Making lemonade from lemons, the necessity is proving to be the mother of invention. The whole issue is finally forcing me to automate certain actions to work around hosting policies.