For Tftpd32 see anticipation window, a checkbox and value in Tftpd32 settings under advanced tftp options.
This is a way to speed up the transfer if the router for some reason times out, try setting value 1024 bytes.
In the case of this particular router, using TFTP to load any of the BS factory-to-ddwrt.img files does not work. I even went back and tried a few other builds just to see if they would work after 46069 didn't (r41517 r42287 r45632).
After those failed attempts which all put the router into boot loop. Used TFTP to load 40270 back onto the router, which worked.
My experience thus far has been that whatever firmware worked or didn't work in the WebGUI gave the same results with TFTP.
I'm not making any claims to what would work on a router that is functioning properly.
U-boot 2012.07 dni1 V0.4 for DNI HW ID: 29764958 NOR flash 0MB; NAND flash 128Me
smem ram ptable found: ver: 0 len: 5
DRAM: 491 MiB
NAND: SF: Unsupported manufacturer 00
ipq_spi: SPI Flash not found (bus/cs/speed/mode) = (0/0/48000000/0)
128 MiB
MMC:
*** Warning - bad CRC, using default environment
PCI0 Link Intialized
PCI1 Link Intialized
In: serial
Out: serial
Err: serial
131072 bytes read: OK
MMC Device 0 not found
cdp: get part failed for 0:HLOS
Net: MAC1 addr:##:##:##:##:##:##
athrs17_reg_init: complete
athrs17_vlan_config ...done
S17c init done
MAC2 addr:##:##:##:##:##:##
eth0, eth1
Hit any key to stop autoboot: 0
(IPQ) #