TRENDnet OEM images
OEM Product Page = http://www.trendnet.com/support/supportdetail.asp?prod=100_TEW-827DRU
I've documented the OEM releases here:
Archive file: fw_tew-827dru_v1(1.00b11).zip
Firmware file: TEW827DRU_FW100B11.bin
Firmware Version: 1.00b11
Release Date: 11/2015
Download URL: http://downloads.trendnet.com/tew-827dru/firmware/fw_tew-827dru_v1(1.00b11).zip
sha256sum: 751e8d997230bc14baf9bd7c85e9e8cd7e2646d0948964707f30fda8b336f8dc
Archive file: fw_tew-827dru_v1(1.02b02).zip
Firmware file: TEW827DRU_FW102B02.bin
Firmware Version: 1.02b02
Release Date: 11/2016
Download URL: http://downloads.trendnet.com/tew-827dru/firmware/fw_tew-827dru_v1(1.02b02).zip
sha256sum: fd70b23a27bf85d3ce0295bcc4a90eebe521c089efcbcf8ef1e00187bf6b609e
Archive file: fw_tew-827dru_v1(1.03b02).zip
Firmware file: TEW827DRU_FW103B02.bin
Firmware Version: 1.03b02
Release Date: 1/2018
Download URL: http://downloads.trendnet.com/tew-827dru/firmware/fw_tew-827dru_v1(1.03b02).zip
sha256sum: 8fb5912754d6927f4172f6377ddadc8214cf1e7937502c3f383dfc053f6eb05d
Archive file: fw_tew-827dru_v1(1.04b01).zip
Firmware file: TEW827DRU_FW104B01.bin
Firmware Version: 1.04b01
Release Date: 9/2018
Download URL: http://downloads.trendnet.com/tew-827dru/firmware/fw_tew-827dru_v1(1.04b01).zip
sha256sum: 22ad93ba1dd0e364f9052aea41917919ea031be7949192897196139312d20332
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The first/original release (1.00b11) has a full firmware image set in it's FIT file, which includes all 13 of the NAND partitions except for the uboot environment part. The newer update releases only have a UBI image within them.
This means that if you want to restore the OEM image to your device, you must first flash the original release image (1.00b11) and then flash the latest updated image. This is necessary to restore a valid bootconfig before updating to the latest release.
Fortunately it looks like you can still download previous image files from TRENDnet's web page, even though they don't have direct links to them published.