almost a third of the 50,000 Chromebooks he manages became "stuck in a state of flickering between a login screen and a 'Network not available' screen." - CTO Sherwin Collette did not respond to a request for comment.

...Six days ago, an IT administrator with Montgomery County Public Schools in Maryland reported that following the update to Chrome version 56, almost a third of the 50,000 Chromebooks he manages became "stuck in a state of flickering between a login screen and a 'Network not available' screen." He also said that some of the roughly 45,000 Windows PCs he manages were affected. The admin said Blue Coat 6.5 doesn't appear to support TLS 1.3.

Attempts to reach the administrator via phone and email were unsuccessful and Montgomery County Public Schools' CTO Sherwin Collette did not respond to a request for comment.
According to Google engineer David Benjamin, the issue is that Blue Coat implements TLS 1.3 incorrectly. "[Blue Coat was] made aware of TLS 1.3 several months ago, but evidently did not test [its] software per our instructions," he wrote. Benjamin did not respond to further requests for comment.

A spokesperson for Symantec, which acquired Blue Coat last year, told The Register in an email, "Symantec has been alerted of a potential issue with TLS 1.3 on selected devices. We're investigating now and are working to resolve the issue."...

https://www.theregister.co.uk/2017/02/27/blue_coat_chokes_on_chrome_encryption_update/