Connection error when remotely managing 10.9 OS X Server (SSL Handshake)
Ok, so after two weeks of not using this feature I tried again and it has now worked (not sure why). The log file says: 

Jan 3 09:13:14 server.XXX.private collabd[329]: [CSUserSessionServiceBase.m:48 4398000 +0ms] Detected Magic Superuser Auth Token –