There is a known issue connecting to Columbus if the client PC running the clients is utilizing Java 8 - see forum post here:
http://forums.cambridgesoft.com/messageview.aspx?catid=55&threadid=3188&enterthread=y
However it has recently come to light that there is also a separate java compatibility issue which might also cause problems when attempting to connect to Columbus via the OMERO clients.
SSL ciphers are not supported by Java 7u85:
http://blog.openmicroscopy.org/tech-issues/2015/07/21/java-issue/
It is necessary to patch the etc/grid/templates.xml file as per the note above but Glencoe have also added a fix for Columbus users in the latest OMERO clients available here:
Windows:
https://perkinelmer.box.com/s/7wya1smajvn0c3v61f9nurg6oqhvtdjj
Mac:
https://perkinelmer.box.com/s/ougp1zc9fy9y4xbcj5k5gyisgp7x4sgn
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- PerkinElmer Technical Support