docker network create fails because of wrong subnet in /run/flannel/subnet.env

[blinkinglight]

Expected Behavior

Current Behavior

source /run/flannel/subnet.env
# docker network create --attachable=true --subnet=${FLANNEL_SUBNET} -o "com.docker.network.driver.mtu"=${FLANNEL_MTU} flannel
Error response from daemon: invalid network config:
invalid subnet 10.5.31.1/24: it should be 10.5.31.0/24

Possible Solution

Steps to Reproduce (for bugs)

1. run etcd on public ip
2. run 1st flanneld -etcd-endpoints [public ip of etcd] and run docker network create --attachable=true --subnet=${FLANNEL_SUBNET} -o "com.docker.network.driver.mtu"=${FLANNEL_MTU} flannel
3. run on 2nd host flanneld -etcd-endpoints [public ip of etcd] and run docker network create --attachable=true --subnet=${FLANNEL_SUBNET} -o "com.docker.network.driver.mtu"=${FLANNEL_MTU} flannel <- this command now fails

Context

https://github.com/flannel-io/flannel/blob/master/Documentation/running.md

Your Environment

• Flannel version: latest from context
• Backend used (e.g. vxlan or udp): vxlan
• Etcd version: latest docker from context
• Kubernetes version (if used):
• Operating System and version: ubuntu 22.04
• Link to your project (optional):