https://bugs.winehq.org/show_bug.cgi?id=37500
--- Comment #29 from Nikos Mavrogiannopoulos nmav@redhat.com --- (In reply to Nikos Mavrogiannopoulos from comment #28)
The issue may be that the application is negotiating SHA256 as MAC, which is 32-bytes instead of the 16-byte SHA1. That reduces the space for data by 16 bytes, and that makes the numbers seen: 16384-16=16368.
Sorry, that's inaccurate as it has nothing to do with SHA256. I checked further and it seems that gnutls will impose an additional penalty to CBC ciphers of a single block size (16 bytes). That explains why 16384 bytes cannot be sent. The solution is the same though.