一台测试用的服务器，每次启动都要卡在一个地方好几分钟，因为不常用，也就没管它。
近两天使用它测试，每次开机太浪费时间了，就去找原因和解决的方法。
首先将报错找出来，对照着敲到百度：a start job is running for wait，果然搜索到解决方法。
解决的方法是修改/etc/systemd/system/network-online.target.wants/systemd-networkd-wait-online.service 文件，在里面加上一句 TimeoutStartSec=5sec
xx@ub:/etc/systemd/system/network-online.target.wants$ cat systemd-networkd-wait-online.service
# SPDX-License-Identifier: LGPL-2.1-or-later
#
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
[Unit]
Description=Wait for Network to be Configured
Documentation=man:systemd-networkd-wait-online.service(8)
DefaultDependencies=no
Conflicts=shutdown.target
Requires=systemd-networkd.service
After=systemd-networkd.service
Before=network-online.target shutdown.target
[Service]
Type=oneshot
ExecStart=/lib/systemd/systemd-networkd-wait-online
RemainAfterExit=yes
TimeoutStartSec=5sec