I believe I am running into the same issue as reported here, but wanted to add some information which may lead to a resolution: https://issues.jenkins.io/browse/JENKINS-52060

In that issue it was found that the server was rejecting a call to "p4 info" when called unauthenticated which as commented on the other issue P4JAVA always does before authentication.

I believe I am attempting to connect to the same semi common server in my industry, if not it has near identical behaviors. I have found it does respond to p4 info unauthenticated if an appropriate user is passed into the p4 info call. It appears to be doing a user validation/error before the standard authentication requirement checks.

So if the credentials are:

P4PORT=ssl:server.network.com:1666
P4USER=John

"p4 -p $P4PORT info" will be rejected
"p4 -p $P4PORT -u $P4USER info" will be accepted as long as the specified user is a valid user on that server, even when not authenticated.

I get this is a non-standard extension on that server so I don't necessarily expect a fix from this side of things. I have reached out to them as well about not validating the user for the "info" command.

If, however, it does not hurt to change the P4JAVA call to "p4 info" right before authentication to include the user then that will likely fix my issue here.