Once upon a time, when the WGT634U wasn’t yet EOL’d, OpenWrt had a bug that caused the flash partition containing the CFE to be erased. As the CFE is the boot loader, you then had a paperweight.
There were rumors one of the two headers on the PCB was a JTAG port, but nobody found out how to utilize it.
Some weeks ago I came across this forum post detailing how to populate the resistor pads to make JTAG work. My WGT634U is now resurrected.