The latest version (1.66.v49c6758b_b_360) of the Trilead API plugin bundles Trilead SSH2 version build-217-jenkins-223.v546f979619d4.

This version changed the behaviour of the maximum packet size, in commit 546f9796 to replace the packet length check from a configurable value (default 65536) to a hard-coded 35000.

This leads to agents throwing an exception and crashing, causing jobs to fail.

14:03:07 Agent went offline during the build
14:03:07 ERROR: Connection was broken: java.io.IOException: Illegal packet size! (64528)

Given that the MAX_PACKET_SIZE constant still exists, I assume this change was unintentional.