https://bugs.winehq.org/show_bug.cgi?id=37500
--- Comment #11 from Robert Munteanu robert.munteanu@gmail.com --- (In reply to Bruno Jesus from comment #10)
From the log: trace:secur32:schan_QueryContextAttributesW Using 256 mac bytes, message size 16384, block size 16
The default max message size is indeed 16384 as specified in the gnutls source code. This value may be changed during the client->server negotiation. I don't know if it's possible to know if it was changed by the server or not.
I'm not very familiar with the wine source code, so this might be a completely off-topic suggestion, but would it not be possible to save the chunk that was not sent and send it with the next method call?