Printer says it's offline
"Offline" usually means the computer can't find the printer on the network. The printer itself is often fine.
What's usually going on
The printer has gone to sleep and not woken properly, dropped off the Wi-Fi, or been given a new address by the router, so the computer is looking in the wrong place. On Windows, a setting can also leave the printer marked as offline on purpose.
Worth trying first
Wake and restart the printer.
Turn it off, wait thirty seconds, and turn it on again. Give it two minutes to rejoin the Wi-Fi before trying to print.
Check its network.
On the printer's screen or a printed network report, confirm it's connected to the same Wi-Fi as your computer, not a guest network.
Clear the queue.
Open the print queue on your computer and cancel every waiting job. One stuck job can keep the printer showing offline.
Windows: turn off "Use Printer Offline".
In the print queue window, open the Printer menu. If Use Printer Offline is ticked, untick it.
Remove it and add it again.
In your computer's printer settings, remove the printer, then add it back so the computer finds its current address.
When to hand it over
If it keeps going offline every few days. That usually needs a change on the router so the printer keeps the same address, which we can make remotely. In New York City, we can sort out the printer in person.
Your own technologist, on call.
Tell us a little about your setup. We'll take it from there.