SYMPTOM 1
No request reaches the TFTP Server
Check this first
Confirm the transfer direction first. If the router should request a file, check the documented recovery mode, Ethernet port and temporary Mac IP.
See which device should send the request ↓
What you should see nextA request appears in the TFTP Server log, including the filename the router wants.
More checks for this symptom
First check the model guide: should the router request a file from your Mac, or should the computer upload it? For a router-request workflow, verify the specified Ethernet port, temporary Mac IP, and recovery-mode timing. Look for a request in the transfer log before changing the firmware. If no request appears, return to the model-specific network and recovery steps rather than trying random IP addresses.
SYMPTOM 2
A request arrives, but the file is not found
Check this first
Compare the requested filename with the file in the served folder. Check letter case and hidden extensions, then verify the exact model, hardware revision and image type.
What you should see nextThe requested file is found and the transfer begins. A permission error needs its own permission check.
More checks for this symptom
Compare the exact requested filename with the file in the folder served by the app, including case and hidden extensions. A file in Downloads is not necessarily in the served folder. Rename it only as the model guide requires, and confirm the firmware type and hardware revision before retrying. The next expected sign is that the requested file is found and transfer begins; an access-permission error needs a separate permission check.
SYMPTOM 3
The transfer starts, then stalls or times out
Check this first
Record where progress stops. Check the Ethernet cable, adapter and specified router port. If needed, allow the app or local TFTP traffic through the firewall. Change one item at a time.
What you should see nextThe transfer reaches the completion signal described by the model guide, without an interrupted connection.
More checks for this symptom
Record the error and the stage where progress stops. Check the Ethernet cable, adapter, specified router port, and whether the connection was interrupted. If firewall permission is needed, allow only the app or local TFTP traffic rather than disabling the entire firewall. Change one item at a time, then look for the transfer-completion signal required by the model guide. Do not apply universal retry counts or transfer settings to every router.
SYMPTOM 4
The transfer finishes, but the router does not boot
Check this first
Follow the model guide for writing time and LED signals. A completed transfer does not prove the image was accepted or written. Check the normal startup address and port, which may differ from recovery mode.
What you should see nextThe device shows the documented startup signals and becomes reachable at its normal address.
Do not interrupt power while firmware may still be writing. If startup still fails after the documented wait, save the model, revision, firmware source and last result before seeking help.
More checks for this symptom
A completed file transfer does not prove that the router accepted, wrote, or booted the firmware. Follow the model guide for waiting time and indicators; do not disconnect power just because the transfer reaches 100%. Check the address and port specified for normal startup, which may differ from recovery mode. If the router still does not start, save the model, hardware revision, firmware source, and error details before seeking model-specific help. When recovery is finished or paused, stop the TFTP service and restore normal network and firewall settings.