Paper player freezes after tunneled login, then hits keepalive timeout on Windows

[minekube-ai-engineer]

Bug description

A user running the Connect Spigot plugin directly on Paper can complete the tunneled login, but the player cannot interact with the world and is kicked roughly 33 seconds later for a keepalive timeout. The tunnel subsequently reports that an established Windows connection was aborted.

Original support thread: https://discord.com/channels/633708750032863232/1535733003307974707

This is separate from the Bedrock principal admission regression fixed in 0.15.4.

Environment

• Windows 11 amd64
• Paper 26.2-111
• Connect Spigot 0.15.3
• Endpoint: el-rio.play.minekube.net
• Direct Connect plugin on Paper; no Gate proxy

Observed sequence

[20:29:14 INFO]: Started watching for new player sessions
[20:29:19 INFO]: Connect tunneled player logged in as bigraul (UUID redacted)
[20:29:20 INFO]: bigraul joined the game
[20:29:53 INFO]: bigraul was kicked due to keepalive timeout!
[20:29:53 INFO]: Connect tunneled player bigraul disconnected
[20:29:53 INFO]: bigraul lost connection: Timed out
[20:30:58 ERROR]: Connection error with TunnelService player=bigraul session=<redacted> tunnelToBackendPackets=3313 tunnelToBackendBytes=47527: java.net.SocketTimeoutException: timeout (cause: java.net.SocketException: An established connection was aborted by the software in your host machine)

The player reports that login succeeds but world interaction never works before the timeout.

Expected behavior

After a successful tunneled login, game traffic and keepalive responses should continue bidirectionally and the player should remain connected.

Notes / triage

• The earlier BedrockPrincipalAdmissionException in the same thread is addressed by 0.15.4 (scope Bedrock principal admission to Bedrock). This report is specifically for the post-login packet stall/keepalive timeout.
• No existing issue matched keepalive, WSAECONNABORTED, or Paper 26.2.
• Suggestions to change Paper's player-idle-timeout or Gate's readTimeout do not apply to this direct-plugin setup.
• Please determine whether the Windows socket abort is the initiating cause or a consequence of the stalled/closed tunnel, and whether 0.15.4 changes the behavior.