Previously, when the agent would attempt to connect to our master, it would get back the following:

Sep 06 06:54:13 internalhostname java[31206]: INFO: Locating server among https://jenkins.domain.tld/jenkins/, https://internalhostname/jenkins/

Since switching from 2.76 to 2.78, and to using the agent.jar instead of the slave.jar, we are getting:

Sep 12 13:30:56 internalhostname java[31206]: INFO: Locating server among https://jenkins.domain.tld/jenkins/, http://internalhostname/jenkins/ 

Please note the change from https to http.

I cannot determine what caused this change however, or where I can configure this.

The problem is that the domain url cannot be resolved from the agent because it tries to connect to the external ip which is only accessible from the office network.

The internal hostname works fine, but only over https, not http.

We start the agent using:

/bin/java -Djsse.enableSNIExtension=false -jar /data/jenkins/agent.jar -noCertificateCheck -jnlpUrl https://internalhostname/jenkins/computer/internalhostname/slave-agent.jnlp -secret ea1459602ecd86fe6ca5393857791b1bf56391febdbb7f4693ffd718399c56c9