我有 2 台远程 PC（Ubuntu 20.04），每天 24 小时运行。除了 之外syslog，我还可以检查我的应用程序写入的日志。有硬件连接到 PC，通过 UDP 与我的应用程序通信。因此，通过硬件，我还可以识别我在这些 PC 上的应用程序是否还活着。
最近我注意到，电脑无法通过互联网端口访问。但我的硬件仍然可以接收通过另一个 UDP 端口发送的包。考虑到电脑不在我身边，我无法登录并查看。
重新启动电脑后，我注意到在我无法访问电脑的时间段内没有系统日志。我那段时间的申请日志也是空的。但我的应用程序必须一直在运行，否则我的硬件会立即通知我（这一点我百分百确定）。
谁能给我一些建议，电脑出了什么问题吗？我还在此附上 syslog，其中涵盖了无法访问的时期。
这Aug 12 15:04:55是我重新启动电脑之前的最后输出。
Aug 12 14:30:29 x3000C kernel: [4063387.125113] ata6.00: configured for UDMA/133
Aug 12 14:30:29 x3000C kernel: [4063387.125125] ata6: EH complete
Aug 12 14:31:29 x3000C systemd[1]: Started Run anacron jobs.
Aug 12 14:31:29 x3000C anacron[976205]: Anacron 2.3 started on 2023-08-12
Aug 12 14:31:29 x3000C anacron[976205]: Normal exit (0 jobs run)
Aug 12 14:31:29 x3000C systemd[1]: anacron.service: Succeeded.
Aug 12 14:39:23 x3000C systemd[1]: Starting Ubuntu Advantage Timer for running repeated jobs...
Aug 12 14:39:23 x3000C systemd[1]: ua-timer.service: Succeeded.
Aug 12 14:39:23 x3000C systemd[1]: Finished Ubuntu Advantage Timer for running repeated jobs.
Aug 12 14:39:55 x3000C snapd[155706]: autorefresh.go:589: Cannot prepare auto-refresh change due to a permanent network error: persistent network error: Post https://api.snapcraft.io/v2/snaps/refresh: dial tcp 255.255.255.255:443: connect: network is unreachable
Aug 12 14:39:55 x3000C snapd[155706]: stateengine.go:149: state ensure error: persistent network error: Post https://api.snapcraft.io/v2/snaps/refresh: dial tcp 255.255.255.255:443: connect: network is unreachable
Aug 12 14:41:41 x3000C ovpn-client[822626]: TLS: soft reset sec=0 bytes=26936/-1 pkts=708/0
Aug 12 14:41:41 x3000C ovpn-client[822626]: VERIFY OK: depth=1, CN=ca
Aug 12 14:41:41 x3000C ovpn-client[822626]: VERIFY KU OK
Aug 12 14:41:41 x3000C ovpn-client[822626]: Validating certificate extended key usage
Aug 12 14:41:41 x3000C ovpn-client[822626]: ++ Certificate has EKU (str) TLS Web Server Authentication, expects TLS Web Server Authentication
Aug 12 14:41:41 x3000C ovpn-client[822626]: VERIFY EKU OK
Aug 12 14:41:41 x3000C ovpn-client[822626]: VERIFY OK: depth=0, CN=server_2023
Aug 12 14:41:41 x3000C ovpn-client[822626]: Outgoing Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key
Aug 12 14:41:41 x3000C ovpn-client[822626]: Incoming Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key
Aug 12 14:41:41 x3000C ovpn-client[822626]: Control Channel: TLSv1.3, cipher TLSv1.3 TLS_AES_256_GCM_SHA384, 2048 bit RSA
Aug 12 15:04:55 x3000C snapd[155706]: autorefresh.go:589: Cannot prepare auto-refresh change due to a permanent network error: persistent network error: Post https://api.snapcraft.io/v2/snaps/refresh: dial tcp 255.255.255.255:443: connect: network is unreachable
Aug 12 15:04:55 x3000C snapd[155706]: stateengine.go:149: state ensure error: persistent network error: Post https://api.snapcraft.io/v2/snaps/refresh: dial tcp 255.255.255.255:443: connect: network is unreachable
Aug 17 13:55:01 x3000C systemd[1]: Starting Flush Journal to Persistent Storage...
Aug 17 13:55:01 x3000C systemd[1]: Activated swap /swapfile.
Aug 17 13:55:01 x3000C systemd[1]: Reached target Swap.
Aug 17 13:55:01 x3000C systemd-modules-load[391]: Inserted module 'lp'
Aug 17 13:55:01 x3000C systemd-modules-load[391]: Inserted module 'ppdev'
Aug 17 13:55:01 x3000C systemd-modules-load[391]: Inserted module 'parport_pc'
Aug 17 13:55:01 x3000C systemd[1]: Finished Create System Users.
Aug 17 13:55:01 x3000C systemd-modules-load[391]: Inserted module 'msr'
Aug 17 13:55:01 x3000C systemd[1]: Starting Create Static Device Nodes in /dev...
Aug 17 13:55:01 x3000C systemd[1]: Finished Load Kernel Modules.
Aug 17 13:55:01 x3000C systemd[1]: Mounting FUSE Control File System...
Aug 17 13:55:01 x3000C systemd[1]: Mounting Kernel Configuration File System...
以下是另一台 PC 的日志记录，Jul 25 12:17:01是最后的输出syslog：
Jul 25 10:56:20 x3000C ovpn-client[1160251]: ++ Certificate has EKU (str) TLS Web Server Authentication, expects TLS Web Server Authentication
Jul 25 10:56:20 x3000C ovpn-client[1160251]: VERIFY EKU OK
Jul 25 10:56:20 x3000C ovpn-client[1160251]: VERIFY OK: depth=0, CN=server_2023
Jul 25 10:56:20 x3000C ovpn-client[1160251]: Outgoing Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key
Jul 25 10:56:20 x3000C ovpn-client[1160251]: Incoming Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key
Jul 25 10:56:20 x3000C ovpn-client[1160251]: Control Channel: TLSv1.3, cipher TLSv1.3 TLS_AES_256_GCM_SHA384, 2048 bit RSA
Jul 25 11:06:44 x3000C whoopsie[1094]: [11:06:44] Cannot reach: https://daisy.ubuntu.com
Jul 25 11:06:44 x3000C whoopsie[1094]: [11:06:44] offline
Jul 25 11:06:44 x3000C whoopsie[1094]: [11:06:44] Cannot reach: https://daisy.ubuntu.com
Jul 25 11:06:45 x3000C whoopsie[1094]: [11:06:45] online
Jul 25 11:17:01 x3000C CRON[1275476]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Jul 25 11:30:01 x3000C CRON[1275603]: (root) CMD ([ -x /etc/init.d/anacron ] && if [ ! -d /run/systemd/system ]; then /usr/sbin/invoke-rc.d anacron start >/dev/null; fi)
Jul 25 11:33:02 x3000C systemd[1]: Started Run anacron jobs.
Jul 25 11:33:02 x3000C anacron[1275629]: Anacron 2.3 started on 2023-07-25
Jul 25 11:33:02 x3000C anacron[1275629]: Normal exit (0 jobs run)
Jul 25 11:33:02 x3000C systemd[1]: anacron.service: Succeeded.
Jul 25 11:56:20 x3000C ovpn-client[1160251]: TLS: soft reset sec=0 bytes=30904/-1 pkts=740/0
Jul 25 11:56:20 x3000C ovpn-client[1160251]: VERIFY OK: depth=1, CN=ca
Jul 25 11:56:20 x3000C ovpn-client[1160251]: VERIFY KU OK
Jul 25 11:56:20 x3000C ovpn-client[1160251]: Validating certificate extended key usage
Jul 25 11:56:20 x3000C ovpn-client[1160251]: ++ Certificate has EKU (str) TLS Web Server Authentication, expects TLS Web Server Authentication
Jul 25 11:56:20 x3000C ovpn-client[1160251]: VERIFY EKU OK
Jul 25 11:56:20 x3000C ovpn-client[1160251]: VERIFY OK: depth=0, CN=server_2023
Jul 25 11:56:20 x3000C ovpn-client[1160251]: Outgoing Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key
Jul 25 11:56:20 x3000C ovpn-client[1160251]: Incoming Data Channel: Cipher 'AES-256-GCM' initialized with 256 bit key
Jul 25 11:56:20 x3000C ovpn-client[1160251]: Control Channel: TLSv1.3, cipher TLSv1.3 TLS_AES_256_GCM_SHA384, 2048 bit RSA
Jul 25 12:17:01 x3000C CRON[1276046]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Jul 31 12:00:56 x3000C systemd-modules-load[390]: Inserted module 'lp'
Jul 31 12:00:56 x3000C systemd-modules-load[390]: Inserted module 'ppdev'
Jul 31 12:00:56 x3000C systemd-modules-load[390]: Inserted module 'parport_pc'
Jul 31 12:00:56 x3000C systemd-modules-load[390]: Inserted module 'msr'
Jul 31 12:00:56 x3000C systemd-sysctl[402]: Not setting net/ipv4/conf/all/promote_secondaries (explicit setting exists).
Jul 31 12:00:56 x3000C systemd-sysctl[402]: Not setting net/ipv4/conf/default/promote_secondaries (explicit setting exists).
Jul 31 12:00:56 x3000C systemd[1]: Finished Remount Root and Kernel File Systems.
Jul 31 12:00:56 x3000C systemd[1]: Activating swap /swapfile...
Jul 31 12:00:56 x3000C systemd[1]: Condition check resulted in Rebuild Hardware Database being skipped.
Jul 31 12:00:56 x3000C systemd[1]: Starting Flush Journal to Persistent Storage...
Jul 31 12:00:56 x3000C systemd[1]: Condition check resulted in Platform Persistent Storage Archival being skipped.
Jul 31 12:00:56 x3000C systemd[1]: Starting Load/Save Random Seed...
Jul 31 12:00:56 x3000C systemd[1]: Starting Create System Users...