Don't use keep-alive for action requests. I found it does not work so well with the Ceton InfiniTV 4. This may need to become a setting in future, because obviously using keep-alive can have some performance benefits.
We've received contact from Ceton to say that they don't think their HTTP stack supports keep-alive... so I've parametised that setting. Also some tweaks to double-triple check that HttpWebRequest instance handling is correct.