I was looking all around the web for this firmware, since mine came with Chinese and no option to change it in the router gui. Luckily a Chinese sellers from aliexpress sent it to me!
So I thought I could share it here, so that if anyone other needs it they won’t have the same struggle finding it.
PS, this firmware isn’t english by default, it requires you to go into settings and change language. There are several videos on youtube explaning this.
Please leave a comment if you have questions.