2024/4/27在升级了Ubuntu后发现隔了一段时间系统就开始不能连接了，网站不能访问。
研究后是系统“睡觉了”。
ubuntu@VM-0-10-ubuntu:/var/log$ sudo tac syslog | grep “is now ASLEEP” | more
Apr 27 19:31:04 localhost NetworkManager[482]: [1714217464.0272] manager: NetworkManager state is now ASLEEP
Apr 27 19:06:14 localhost NetworkManager[483]: [1714215974.6164] manager: NetworkManager state is now ASLEEP
Apr 27 18:08:40 localhost NetworkManager[498]: [1714212520.6616] manager: NetworkManager state is now ASLEEP
Apr 27 17:35:34 localhost NetworkManager[498]: [1714210534.3099] manager: NetworkManager state is now ASLEEP
Apr 27 17:04:04 localhost NetworkManager[523]: [1714208644.0798] manager: NetworkManager state is now ASLEEP
参考了：
https://zhuanlan.zhihu.com/p/415661679
执行如下命令后，系统就不“睡“了
ubuntu@VM-0-10-ubuntu: sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target
其他可参考的文章：
https://cloud.tencent.com/developer/ask/sof/116457464
https://github.com/systemd/systemd/blob/main/src/sleep/sleep.c
https://cloud.tencent.com/developer/article/1516125