RT150M

This device is NOT RECOMMENDED for future use with OpenWrt due to low flash/ram.
DO NOT BUY DEVICES WITH 4MB FLASH / 32MB RAM if you intend to flash an up-to-date and secure OpenWrt version onto it! See 4/32 warning for details.

1) This device does not have sufficient resources (flash and/or RAM) to provide secure and reliable operation.
This means that even setting a password or changing simple network settings might not be possible any more, rendering the device effectively useless. See OpenWrt on 4/32 devices what you can do now.

2) OpenWrt support for this device has ended in 2022.
19.07.10 was the last official build for 4/32 devices.

Also know as Pacific Networks RT-150M (9V power adaptor version), this is a TL-WR741ND v1 rebrand for Pacific Networks, and will only accept firmware with Pacific Networks vendor bytes (in the file header). Others 3rd party(OpenWrt/DD-Wrt/TP-Link) firmwares does not have those bytes. This is identical to Multilaser RE027 router. Pacific Networks did not have any firmware available to copy vendor bytes but they were found out and are shown below.

Steps:

Download this tool: Firmware_hardware_ID_modifier.exe. The software is in Chinese, but it's really simple to use, you do not need to see the menus.
Download the oldest firmware from TP-Link WR741ND v1 webpage.
Open the software, choose the original firmware, than change the values: first col (0x40-0x43) repeat code 07410001, and next col (0x44-0x47) write 00300001.
Some message will show in the software, about 5 lines. Then the original firmware was changed (check date modified of file).
Open your browser, and do the firmware update normally. (don't do this through wireless).
After that, your router will restart with TP-Link original firmware.

For next firmware update, you DON'T need to change the vendor bytes again, just download the latest firmware from TP-Link website and proceed to update.

All new mod/change now can be done according the original wiki page of TL-WR741ND.

Not tested yet, but should work same as TP-Link WR741 compatibility page.

All the internal images are the same as RNX-N150RT and TL-WR741ND v1/v2.