断开连接后,Ubuntu Server 20.04 netplan静态IP下降

我正在使用netplan为机器上的多个以太网端口设置静态IP地址。它们会一直工作,直到断开电缆连接,然后再重新连接。当我拉电缆并将其重新插入时,该适配器上没有IP地址。

My 00-netcfg.yaml file looks like this. I don't have any other yaml files in /etc/netplan

network:
  version: 2
  renderer: networkd
  ethernets:
    enp9s0:  # port 1
      dhcp4: no
      addresses: [10.0.70.1/24]
      gateway4: 10.0.0.1
      nameservers:
        addresses: [192.168.64.5, 192.168.64.13, 8.8.8.8, 8.8.4.4]
      optional: true
    enp10s0: # port 2
      dhcp4: no
      addresses: [10.0.70.2/24]
      gateway4: 10.0.0.1
      optional: true
      nameservers:
        addresses: [192.168.64.5, 192.168.64.13, 8.8.8.8, 8.8.4.4]
    enp11s0:  # port 3
      dhcp4: no
      addresses: [10.0.70.3/24]
      gateway4: 10.0.0.1
      optional: true
      nameservers:
        addresses: [192.168.64.5, 192.168.64.13, 8.8.8.8, 8.8.4.4]

I found a few posts suggesting adding link-local: [] entries for each adaptor and disabling ipv6 by adding GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1" in /etc/default/grub but no joy. Suggestions gratefully received