症状：Ubuntuでネットワークに接続できない

解決方法：時刻を合わせる

やり方：

・現状確認

mma@mma-B760-DS3H-DDR4:/etc$ timedatectl
               Local time: 木 2023-05-25 11:07:53 JST
           Universal time: 木 2023-05-25 02:07:53 UTC
                 RTC time: 木 2023-05-25 02:07:53
                Time zone: Asia/Tokyo (JST, +0900)
System clock synchronized: no
              NTP service: active
          RTC in local TZ: no
mma@mma-B760-DS3H-DDR4:/etc$ sudo systemctl status systemd-timesyncd.service
[sudo] password for mma: 
● systemd-timesyncd.service - Network Time Synchronization
     Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; ve>
     Active: active (running) since Thu 2023-05-25 11:00:24 JST; 8min ago
       Docs: man:systemd-timesyncd.service(8)
   Main PID: 603 (systemd-timesyn)
     Status: "Idle."
      Tasks: 2 (limit: 38237)
     Memory: 1.4M
        CPU: 44ms
     CGroup: /system.slice/systemd-timesyncd.service
             └─603 /lib/systemd/systemd-timesyncd

 5月 25 11:02:49 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:02:59 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:03:09 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:04:24 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:04:34 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:06:52 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:07:03 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:07:13 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:07:23 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
 5月 25 11:07:33 mma-B760-DS3H-DDR4 systemd-timesyncd[603]: Timed out waiting f>
lines 1-22/22 (END)...skipping...

・ntpの設定追加

mma@mma-B760-DS3H-DDR4:/etc$ sudo nano /etc/systemd/timesyncd.conf

-変更点

#NTP=　→　NTP=sunrise.mma.club.uec.ac.jp

・リスタート

mma@mma-B760-DS3H-DDR4:/etc$ sudo systemctl restart systemd-timesyncd.service

・最後に確認

mma@mma-B760-DS3H-DDR4:/etc$ sudo systemctl status systemd-timesyncd.service
● systemd-timesyncd.service - Network Time Synchronization
     Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; ve>
     Active: active (running) since Thu 2023-05-25 11:15:33 JST; 17h left
       Docs: man:systemd-timesyncd.service(8)
   Main PID: 4698 (systemd-timesyn)
     Status: "Initial synchronization to time server 192.168.1.254:123 (sunrise>
      Tasks: 2 (limit: 38237)
     Memory: 1.3M
        CPU: 41ms
     CGroup: /system.slice/systemd-timesyncd.service
             └─4698 /lib/systemd/systemd-timesyncd

 5月 25 11:15:33 mma-B760-DS3H-DDR4 systemd[1]: Starting Network Time Synchroni>
 5月 25 11:15:33 mma-B760-DS3H-DDR4 systemd[1]: Started Network Time Synchroniz>
 5月 24 17:15:38 mma-B760-DS3H-DDR4 systemd-timesyncd[4698]: Initial synchroniz>

終了