Firmware archive for the TP-Link TD-W8901N modem router, UN regional version, hardware version 3, build dated 171115 in the name. Router firmware like this is normally installed through the device's web interface update page, or written straight to the flash chip with a programmer if the unit no longer boots. Match the hardware version on the label under the router before flashing, because firmware for another version can brick it. Keep the power stable during the update, and save a backup of the existing flash whenever possible.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @biositechyangiyer. Enginerys does not host this file.
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Compressed archive that every operating system opens without extra software.