oleg_nenashev Yes, i'm running LTS. I just saw that i entered a wrong version number, it's 2.89.2 of course, sorry about that.

Please tell me if i shoud try another version / how i can provide additional information.

oleg_nenashev naensma I think i just found some kind of solution:

When i enter my connection string as 'Jenkins Tunnel' instead of 'Jenkins URL', my clients seem to be able to connect to the master.

Does this make any sense?

I am hitting the same issue. 

Background

Jenkins is running in an on premise kubernetes cluster.

NAME     READY     STATUS    RESTARTS   AGE     IP                NODE 
jenkins-0 1/1          Running   0                 5s        10.43.0.2     nem-docker-app-node05.inter-olymp.local

There are two service exposed as NodePort. One for jenkins using NodePort 30100 and one for the slave port using 30200, which is set to 50000

NAME                   TYPE                 CLUSTER-IP           EXTERNAL-IP    PORT(S)                    AGE     SELECTOR
jenkins                  NodePort         10.96.191.11          <none>            8080:30100/TCP       8s        app=jenkins
jenkins-agents      NodePort         10.108.78.226        <none>            50000:30200/TCP     8s        app=jenkins

I browse to my Jenkins instance using port 30100, e.g. http://build.mydomain.com:30100 and create a new permanent agent called test.

What I Expected

Execute the following command and the slave agent connects to Jenkins.

java -jar agent.jar -jnlpUrl http://build.mydomain.com:30100/computer/test/slave-agent.jnlp -secret c80dc7812095e908d9807b83dbb7406f03f8274f83f70ca407e9fcec2665ed7a -workDir "C:\Jenkins"

What Happened

I get a 404 not found.

Oct 19, 2018 9:57:45 AM org.jenkinsci.remoting.engine.WorkDirManager initializeWorkDir
INFO: Using C:\Jenkins\remoting as a remoting work directory
Both error and output logs will be printed to C:\Jenkins\remoting
Failing to obtain http://build.mydomain.com:30100/computer/test/slave-agent.jnlp?encrypt=true
java.io.IOException: Failed to load http://build.mydomain.com:30100/computer/test/slave-agent.jnlp?encrypt=true: 404 Not Found
at hudson.remoting.Launcher.parseJnlpArguments(Launcher.java:496)
at hudson.remoting.Launcher.run(Launcher.java:322)
at hudson.remoting.Launcher.main(Launcher.java:283)

Additional Info

Browsing to http://build.mydomain.com:30200>/ gives

Jenkins-Agent-Protocols: JNLP4-connect, Ping
Jenkins-Version: 2.121.3
Jenkins-Session: bb58e25a
Client: 10.42.0.0
Server: 10.43.0.2
Remoting-Minimum-Version: 2.60

So I am not sure what is going on here. The agent port is reachable through NodePort 30200. It sends traffic to 50000. But the slave-agent.jnlp is not found

JENKINS-53461 is Jenkins Remoting should address this issue for Cloud-Native platforms by removing reliance on the TCP endpoint

I hit the same issue, but finally fixed because I hit the wrong port

there are two default ports: 8080 and 50000 

50000 is jnlp port, but when you connect to tcpSlaveAgentListener, you should use 8080

 curl localhost:8080/tcpSlaveAgentListener/