The Draytek support site says this:-
Apple's Mac OS X operating system has a command line TFTP utility that can be used to send firmware to a DrayTek router that is in TFTP mode
Here is how to do it:-
Step 1. Download the firmware from the DrayTek UK Downloads page, avoid beta firmware versions because those may not include the .rst file required to reflash the router back to factory default settings.
Step 2. Extract the .zip file from that page to the root of your user directory i.e. in Finder, under Places, select your user account and put the firmware in that folder. It needs to be in this location so that it can be easily accessed when using the Terminal command line interface.
Step 3. Connect the computer directly to the router's LAN ports and reconfigure the IP address on that LAN interface with a Static / Manual IP in the 192.168.1.x range, this would usually be 192.168.1.10:
IP Address: 192.168.1.10
Subnet Mask: 255.255.255.0
Gateway: 192.168.1.1
Step 4. In Finder, go to Applications then Utilities and open Terminal
Step 5. Enter these commands into the Terminal window:
(replace v2820pbx_a9_[3571].all with the file name of the firmware being sent)
> tftp 192.168.1.1
> binary
> rexmt 1
> timeout 180
> put v2820pbx_a9_[3571].all
That will then wait three minutes (timeout 180) for the router to receive that firmware.
Step 6. At this stage, it is necessary to put the router into TFTP mode:
1. Power off the router
2. Press and hold the Factory Reset button
3. While still holding the Factory Reset button, turn the router back on
4. The router should then power up with the three lights on the left flashing, or on routers with a row of LEDs, the ACT light and the adjacent LED flashing.
5. Let go of the Factory Reset button.
Step 7. Roughly 30-40 seconds after turning the router on in TFTP mode, the Terminal window will show a message such as:
Sent 6210656 bytes in 91.0 seconds
Which indicates that the firmware has finished sending - leave the router to reflash itself for 3-4 minutes (less on newer models such as Vigor 2860), until the ACT light is blinking on the router again which indicates that it's back to normal operation.
Step 8. When the router is back online, it will be possible to log in to the router's web interface. If the .rst firmware was sent to the router, it will be accessible on 192.168.1.1 and the router will be running on Factory Default settings. If the .all firmware was sent to the router, set the computer's IP address back to its original setting and access the router as normal.
