11.5.10.2 : connection error while applying patch

Hi,
when applying the patch 17065255.

Unable to get the database connection using schema username/passwordIo exception: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=186647296)(ERR=12514)(ERROR_STACK=(ERROR=(CODE=12514)(EMFI=4))))


the log files are showing :
========================================

Screen and Log excerpts for failed patch application.

Screen output from execution of adpatch command: (u17065255.log contains much the same)
…
…
There are now 23 jobs remaining (current phase=A0):
   4 running, 0 ready to run and 19 waiting.

  FAILED: file pji_fp_aggr_pjp3.xdf on worker  3 for product pji username APPS.
Deferred: file pji_fp_aggr_pjp3.xdf on worker  3 for product pji username APPS.               (Deferment number 2 for this job)