如何在18.04中避免5分钟的启动延迟：“正在运行Raise网络接口的启动作业”

问题：启动延迟5分钟

设备：UP板（小型x86板），运行18.04，带有Panda PAU05无线USB适配器，通过HDMI连接到监视器

网络配置：使用netplan和systemd-networked。未安装NetworkManager。

连接以太网后，设备会快速启动。我可以拔掉以太网并依靠wifi。SSH可以工作，等等。

如果未连接以太网，则会有5分钟的延迟。控制台会说，A start job is running for Raise network interfaces (Xmin Ys / 5min 2s)并慢慢计数最多5分钟2秒。我可以ping设备，但ssh被拒绝：ssh: connect to host rodeobot.local port 22: Connection refused。5分钟后，启动完成正常。

我对netplan进行了修改，以使以太网和wifi接口都是可选的，但这无济于事。我还尝试删除了以太网接口，但这没有帮助。这是/etc/netplan/config.yaml我现在正在运行的：

network:
  version: 2
  renderer: networkd
  ethernets:
    enp1s0:
      optional: true  # Don't wait for Ethernet
      dhcp4: true
  wifis:
    wlx9cefd5fcb328:
      optional: true  # Don't wait for Wifi
      dhcp4: true
      access-points:
        "xxx":
          password: "yyy"

编辑：我看到了几个类似的问题，但没有看到使用netplan的答案。这是netplan中的错误/缺失功能吗？

编辑：固定缩进和注释在config.yaml中。（我复制并粘贴，然后编辑了ssid和pw。）

编辑：这是的结果sudo netplan --debug generate：

** (generate:965): DEBUG: 18:35:38.361: Processing input file /etc/netplan/config.yaml..
** (generate:965): DEBUG: 18:35:38.362: starting new processing pass
** (generate:965): DEBUG: 18:35:38.362: wlx9cefd5fcb328: adding wifi AP 'Beckett'
** (generate:965): DEBUG: 18:35:38.362: wlx9cefd5fcb328: setting default backend to 1
** (generate:965): DEBUG: 18:35:38.362: Configuration is valid
** (generate:965): DEBUG: 18:35:38.362: enp1s0: setting default backend to 1
** (generate:965): DEBUG: 18:35:38.362: Configuration is valid
** (generate:965): DEBUG: 18:35:38.363: Generating output files..
** (generate:965): DEBUG: 18:35:38.363: NetworkManager: definition enp1s0 is not for us (backend 1)
** (generate:965): DEBUG: 18:35:38.363: wlx9cefd5fcb328: Creating wpa_supplicant configuration file run/netplan/wpa-wlx9cefd5fcb328.conf
** (generate:965): DEBUG: 18:35:38.363: Creating wpa_supplicant service enablement link /run/systemd/system/systemd-networkd.service.wants/[email protected]
** (generate:965): DEBUG: 18:35:38.364: NetworkManager: definition wlx9cefd5fcb328 is not for us (backend 1)

谢谢。