@Dooberino 

Normally there is nothing to be configured on the main router (the AX50 in your case). You connect the "client" router to the main router via the client router's WDS setup and that's it. Can you tell us the make and model of your old router?

@woozle yeah. I have a TP-Link Archer C7 v2 that I flashed with DD-WRT.

@Dooberino 

Some time ago I've had an old WR841N router with DD-WRT running as a range extender connected to my AX50.

I can't recall now how I set it up at the time though. I do remember it took me a couple of unsuccessful attempts, but eventually I had it working.

Commercial routers with their original firmware will usually adjust all depending router settings automatically when you enable WDS or Repeater mode on them.

With DD-WRT you will have to adjust all depending settings on your own. 

I recommend you search for setup guides on the Internet and follow them. In case the C7 doesn't successfully connect and you are locked out of it, you will have to perform a Factory Reset via the hardware button and then try again, perhaps using another setup guide from someone else.

@woozle I figured that is end up here. But, I'm happy you got your to work. You said that you had it before. Why'd you drop your ddwrt router as extender?

@Dooberino 

Because the AX50's signal is quite weak at the farthest point of my apartment I tried to improve that by using the old WR841N as range extender for 2.4 GHz, placed about halfway in between the AX50 and that farthest point, using the same SSID as the AX50 for simplicity.

By design, the maximum data transfer speed through the repeater's Wi-Fi is only half that of the regular Wi-Fi throughput, in reality even less.

The problem now was that client devices were often connected to the (slow) repeater router even if they were close enough to the AX50 to receive a sufficient signal from it.

I also tested using a different SSID for the repeater and switching the client devices manually if needed, but that wasn't satisfactory either, as it was too much effort for a small gain.

I have ran a few tests with AX-50 on stock - and client with openwrt. It seems that AX-50 does NOT support WDS - which is quite dissapointing. No fimware updates for over a year now, they have removed planned support for Mesh, and no WDS support. Seems that you get what you pay for ...

@Dooberino Hi there, how were you able to enable WDS on your Archer AX-50 ? I have been through all the various online suggestions ( for different versions of the firmwares out there ) and do not see the WDS option under 2.4Ghz 

Hey, @Zodan . No, I don't have that on mine either. I have v1.0 of the router, by the way.

I've kind of given up on that bit for now because I'm pretty certain there's a good chunk of bandwidth already lost with that. I'm planning to find ways to route cabling through the walls instead.

I hope you find better luck on your end though.