SOLVED Rancher VM becomes unreachable after adding first Host

[NetSoerfer]

So for a while I've been trying to get a RancherOS based docker infrastructure to work, following dublea's [How To] FreeNAS-11.1-U2 + RancherOS + Plex (Migrate from Jail) + Tautulli + Plex Requests, but the Rancher VM becomes unreachable soon after I've added the first docker host. I can briefly access the Rancher web UI, but before long it becomes unavailable, as does the SSH server on the VM. The only way to access the VM is through the FreeNAS shell ( cu -l /dev/nmdm12B). This keeps happening even after rebooting the RancherOS VM.

My home network consists of multiple subnets in the 10.42.0.0/16 range (e.g. 10.42.1.0/24), which is the default managed network RancherOS uses, but I think I've mitigated that by configuring a different subnet for RancherOS to use. What am I doing wrong?

 

[NetSoerfer]

Solved it. Even though I had updated the Cattle environment template configuration to use a different subnet, I had then neglected to create a new environment using that template. Creating a new environment using the updated template and deleting the old environment - highlighted in red below - finally did the trick.

To prevent Rancher from using a subnet that will collide with any existing subnets you may have in the 10.42.x.x range, set a different managed network in the Cattle Environment Template (see attached screenshots if you can't find where to do the below steps):

• Go to Manage Environments
  
• Edit the Cattle Environment Template
• Scroll to the Networking services and click Edit Config for the Rancher IPsec service
• In the Configuration Options section, change the Subnet variable to an unused subnet
  (note that this is a /16 subnet - so if you set 10.32.0.0/16, Rancher will use up the entire IP range from 10.32.0.0 to 10.32.255.255!)
• Scroll down and click Configure to return to the Environment Template, then don't forget to scroll all the way down to actually Save the Environment Template's changed configuration!

After updating the template, you must create a new environment - the environment created by default won't be updated with the new managed network settings. In Manage Environments, create a new environment using the Cattle template, set it as default, Deactivate the old environment and then Delete it.