Understanding Vault errors 27919 and 27915

Vault 5.3, 5.4, 5.5, 6.0, 6.1
What causes Vault errors 27919 and 27915?

Vault errors 27919 and 27915 can have different root causes, but 27919 indicates some sort of socket error.  The actual value can vary depending on the problem, in this case (see log excerpt below) it is 10053.  The error code 10053 is a winsock error code that can be deciphered with 'net helpmsg' as follows:

ERROR 10053 and 10054
09:57:46 ERROR 27919: send aborted due to socket error 10053
09:57:46 ERROR 27915: socket error [10053]
from the command line on the Vault server, type
net helpmsg 10053
C:\Documents and Settings\Administrator>net helpmsg 10053
An established connection was aborted by the software in your host machine.
Usually this occurs when a socket connection exceeds the internal timeout thresholds.
As you can see from the log, the "normal" next line would be:
10:01:40 sent [18001] bytes, generation [637] ms, transmission [12] ms
UPDATED:  July 16, 2019