Unavailable docker TCP ports

Hi everyone!

I am currently having an issue with PFC200 and exposed ports.

Upon bootup, two docker containers start successfully and are forwarded to ports:

  • Node-RED>1880/tcp,>8090/udp
  • InfluxDB>8086/tcp,>8089/udp

After a short while, external device (laptop) can easily connect to both ports.

Problem starts when ethernet connection is disturbed (by pulling a cable out) and reestablishing connection. Ports are still exposed and I have checked that processes on PLC are still running, but external device cannot connect to containers anymore given exposed ports. Restarting containers doesn’t fix the issue - the only way to fix it is to reboot controller.

I have checked and clear IPtables which also doesn’t solve the issue.

All other services like wbm or codesys visualisation work just fine.

Both containers are part of user-defined network with bridge model and fixed IP addresses within it.

I am trying to understand why is this happening - has anyone came across this before or have an idea what could be an issue?

Kind regards,


Please see this post:


Thank you Kurt for a prompt reply,

First I was certain ipv4 forwarding was enabled when running command:

sysctl net.ipv4.ip_forward


But then followed your advise on checking conf file itself:

nano /etc/sysctl.conf

and there it is, set to 0!


Seems like every day is a school day :slight_smile:

Thank you