Hello,
I just compiled latest TrinityCore from source on Debian (commit a834c66a4e637edfc1d271daf3c64468fb8c731f), run worldserver and bnetserver without error and correct configuration, patched client Wow.exe from Battle.net with connection_patcher, changed "portal" in Config.wtf.
When I try to login with WoW_patched.exe, I get the message "You have been disconnected. (BLZ51901016)"
I sniffed network packet from this executable and the binary does connect to my server.
Thank you for helping !