Add mention of 'Protocol' failure for IPv6 (rebased onto develop)



This is the same as gh-835 but rebased onto develop.

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See:
 * https://github.com/openmicroscopy/openmicroscopy/pull/2689 for more information.
 * https://www.openmicroscopy.org/community/viewtopic.php?f=5&t=7546