This page talks about how to backup entire flash content on your TP-Link router WR703N, so a restore can be done if something messed up.
If you want to backup u-boot only:
cat /dev/mtd0 > /tmp/backup_u-boot.bin
To backup ART partition only:
cat /dev/mtd4 > /tmp/backup_art.bin
To backup firmware with settings:
cat /dev/mtd5 > /tmp/backup_firmware.bin
To backup full flash:
cat /dev/mtd0 > /tmp/backup_fullflash.bin cat /dev/mtd5 >> /tmp/backup_fullflash.bin cat /dev/mtd4 >> /tmp/backup_fullflash.bin
now copy bin file(s) from tmp dir on router in your computer via WinSCP.