Take a look at the products supplied by GL.iNet to see if any fit your application. These are all supplied with openwrt. I have a Slate and a Creta as wireless routers behind my ISPs router (with the wireless turned off) to cover my house.
OK, I understand that. Do you have a raspberry pi3 or pi4. (or a pi1 or pi2 with usb wireless)?
They can make a temporary router to get you by for a while. I found them a bit tricky to set up, but this is made easier with a console cable to make sure you keep control. When you have finished with it you can go back to raspbian, or whatever.
No I haven't any of these. I hope I just will find some thing appropriate on my market.
Yes. You right. I tried that way. And ended up with TP-Link Archer A7. It was an epic fail. Like people here says it's not really good device nowadays. It's not the worst. This device don't wanna flash.
So I decided to go other way.
I'll try to narrow down search area a little bit. In my contry most popular brands are Asus, Zyxel, D-Link, TP-Link, Netgear.