WRT400N is not Broadcom chip based. Its Atheros instead and that is not supported.
Serial Num. = MUJ00
FCC ID = Q87-WRT400N
Industry Canada ID = 3839A-WRT400N
OEM Gemtek = WRTA-244N (WRTA-244N_V02)
CPU Type = Atheros AR7161 rev 2 (0xaa)
MIPS Rev = ?
CPU Speed = 680MHz
Bus = ?
Flash Type = Serial
Flash Chip = Winbond W25X64Vf1G 0920
Flash Size = 8MB
Max Firmware Size = 7995392 bytes
RAM Size = 32MB
RAM Chip = Winbond W94525G6EH-5
nvram Size = Set by firmware
Switch = Atheros AR8216
Don't get disappointed. You can still run a 3rd party firmware DD-WRT on it and accomplish your VLAN requirement.
Have a great day
I learn something new from everyone everyday. A hardware and software hacker .
My Routers: Buffalo WHR HP G54, WRT54G-TM, WRT54GL, ASUS RT N16, DLINK DIR600, Linksys E3200, Tplink 1043ND, ASUS RT N13B, Alfa R36