Dump the flash over serial or see if there is tftp support (or maybe nfsv1) These bootloaders usually support high-speed serial (maybe even up to 921600 baud).

Dump the flash over serial or see if there is tftp support (or maybe nfsv1) These bootloaders usually support high-speed serial (maybe even up to 921600 baud). Alternatively, if it supports tftp, the transfer would be trivial (ha). I recently had to download flash via serial converting an aerohive with old firmware to ddwrt. Bootloader supported Kermit, xmodem, and ymodem.... really brought me back!