Got the WNDR3400 today from Goodwill.
This one looks ok, the system seems to boot up better than the unit I had yesterday.
Unfortunately the serial console was a challenge to solder cause they were surface mount.
Also the connections online do not seem correct. Here is how I connected them
Flashing was relatively easy, but I had to run
brctl addif br0 vlan1
nvram save
nvram commit
On the serial console.
Luckily I went through the effort of attaching one.