Written 26 Aug 2026. This is a how-to, not a product card.

When something broke, look at the log

SSH works, but a house job doesn't. Read the program's recent log before you buy a monitoring box.

SSH from the couch works. A house job does not: ads are back, the share vanished, or a restart after a reboot did not help. Read that program's recent log. You are not buying a monitoring box for this look.

Skip until SSH works

If ping fails and SSH hangs, start with is the computer still on? If you have never logged in from the couch, that is SSH from the couch. If the computer is off, fix that first. This note assumes you can log in from the couch.

Skip until you know which job failed

If you just rebooted and have not checked the house jobs yet, start with after a reboot, check the computer still does its jobs. If ads are back, that is when ads come back, check the ad block. If the share vanished, that is when the house share disappeared, check the computer. This note is the next look when systemctl said inactive, or a restart did not help.

What this is

A log records messages from programs. journalctl is the Debian/Ubuntu tool that reads those messages. You are reading recent log entries from one program. You are not installing Grafana. You are not buying a monitoring appliance.

Check one service

SSH in from the couch. Check the job that failed, not the whole computer. For house ad block:

systemctl status pihole-FTL

For the house share:

systemctl status smbd

Then read the recent log lines for that same program. For Pi-hole:

journalctl -u pihole-FTL -n 50 --no-pager

For Samba:

journalctl -u smbd -n 50 --no-pager

-u picks the program. -n 50 is the last fifty lines. --no-pager prints them without a scrolling trap.

If the name is wrong

If systemctl says the unit wasn't found, don't invent a fancy name. List the services that failed:

systemctl list-units --type=service --state=failed

That list shows the service names. Stick to the jobs this site already named: Pi-hole as pihole-FTL, Samba as smbd. Don't chase exotic unit names that are not on this site.

What to do with what you see

Read the last lines. A clear error about a full disk is see if the computer still has room, then clear old package downloads when the disk is tight, then clear old logs when the disk is tight. Permission or firewall is turn on a simple firewall without locking yourself out. Otherwise copy the last error lines into a note for yourself and re-check the matching how-to. Don't paste logs to strangers on day one.

What next

Leave it. Skip a monitoring box. Skip a NAS. Skip opening SSH to the internet. If the computer feels slow, later: see if the computer still has free memory. Weekly habit stays keep the computer updated.

Skip

• Skip if SSH fails. That is is the computer still on? or SSH from the couch.
• Skip if nothing is broken.
• Skip Grafana or Prometheus tonight.
• Skip a second computer.
• Skip buying a KVM because a log line scared you.