Most likely causes:
Bustle can't access the printer - Make sure Local Network access is turned on for Bustle. Go to iPad Settings > Apps > Bustle > Local Network
Printer or hardware (paper jam / hardware / cables).
A glitch on your network / router.
iPad Wi-fi has moved to another network.
Step 1 - check the iPad first (this fixes most issues)
Go: Home → Settings → Wi-Fi.
Make sure the iPad is on the same network/router as the printer. If you see other networks listed, forget the extra ones so the iPad can’t jump.
Step 2 - printer lights quick check
Flashing blue/green: printer can’t reach the router.
Check power, unplug and reset cables on the printer and at the router
Solid blue/green: printer is connected - check the iPad.
Close Bustle > Restart iPad > Check Wi-Fi
Search for printer in bustle
Can find it but can't print? (If Epson - try reselecting the printer model - Epson Ethernet then try test print again). Also - check this network setting on the iPad
Can't find printer - Turn printer off and on for 10 seconds then try again.
Red: paper or hardware - check paper, Check power and cables.
Step 3 - quick actions
Unplug the printer cable(s) and plug them back in (try another Ethernet/USB cable if you have one).
Power-cycle the printer: Off → wait 10s → On.
In Bustle: Settings → Printers → Search for printers → Select → Test print. (If Epson - try reselecting the printer model - Epson Ethernet then try test print again)
If printers don’t show, close Bustle and restart the iPad, then try again.
Router reboot (when all else fails)
Turn the router off for a full 3 minutes (time it).
Turn it back on and wait a couple of minutes for everything to come up.
Then in Bustle, Search for printers again and test print.
If it’s still not printing
If the light stays red it's a possible hardware fault and may need to be replaced or fixed.
Contact us - before you do, having these ready will speed up the process :
iPad model, which printer model, what the printer light is doing, whether you rebooted the router, and when the problem started.