The first part of connecting to a server happens very fast, but the second part times out. Turns out the issue arises because the client machine we are testing on runs ESET Smart Security
http://www.eset.co.uk/Home/Smart-Security and presumably blocks the incoming UDP transport required for NTP to work. Funnily, it is the ESET Antivirus featureset not the ESET firewall featureset that does the blocking somehow. This puts us in a difficult situation, because we cannot ask our clients to configure their firewalls or antivirus solutions, correcting UTC needs to work without local user intervention. So the only idea right now is to use the Time or the Daytime protocol, but the blocker there is we could not find any servers we could use these protocols with? Do you know any (reliable) Daytime or Time servers we could use?