The TP-Link EX220 router, commonly provided by the ISP MTS, exists in two hardware revisions. While the v1 version is officially supported by OpenWrt, the specific revision labeled 'EX220(RU)MTS Ver:1.30' features a different NAND flash chip, making standard OpenWrt images incompatible.
The author successfully ported OpenWrt to the NAND-based revision by utilizing the original bootloader and adjusting the kernel and root filesystem layout. The process requires a UART connection with 3.3V levels at a speed of 115200 baud. The implementation ensures that sysupgrade remains functional and provides approximately 24 MB for the overlay partition.
A key challenge involved extracting radio calibration data, which is stored as a compressed file within the JFFS2 filesystem rather than in a dedicated flash partition. The author developed a script to mount the partition and provide the calibration data to the driver, ensuring proper Wi-Fi performance.
The support for this specific hardware revision has been submitted to the official OpenWrt repository as pull request #24831. Maintainers require additional testing from other users to verify that the calibration and memory layout are consistent across different units before merging the patch.
Owners of the EX220(RU)MTS Ver:1.30 router can assist by providing photos of the device label or testing a provided image in RAM via a UART adapter. Once the patch is accepted, official OpenWrt support will enable users to replace the provider firmware on these devices.
