This router has JTAG port but uses 128MB NAND flash.
This router use 14 pin EJTAG port.
When soldering pin header, you need to use 90 degree pin header or slightly modify the pin header and connector of the female connector.
This is to allow the cover to close without any issue.
The tool to debug the CPU is EJTAG (non-DMA). 0.78 with MR18 data file to program SPI flash.