Apparently Polycom VVX UC software 188.8.131.5237 require that lyncdiscoverinternal point to internal IP, if not it will product a very "descriptive" error:
SSL_get_error Error code=5,rc(0)
The workaround is to disable lync autodiscover and point directly to an internal host:
or in the phone advanced menu in sign-in dialog.
or change lyncdiscoverinternal to point back home.
It looks like this is a new situation, as it seems older versions worked ok.