@RainSong Apparently the WDS feature has been removed in newer firmware versions in favor of OneMesh. I am not sure if its possible, but you could try to go back to a pre-OneMesh firmware.

@ameed That looks like a good cable. The "0.5" should indicate 0.5 mm2 wire thickness (about 20AWG). Given the current you measured for the newer router the voltage sag over this 25 m long cable...

@ameed Like I've indicated ealier, it depends on a few factors. One way to make it work for sure would be to route a 25 meter long mains voltage extension cord (115V or 230V, whatever is used in your...

@ameed Without a detailed look at the electronic components inside the router it is impossible to predict what would happen if you power it with a 12V DC adapter. After all, when the router has...

@ameed Okay. Then maybe the long cable is catching a lot of RF noise that the newer router somehow can't deal with. Do you happen to have one of those clip-on ferrite cores somewhere around the house...

@ameed The new router is probably just somewhat more susceptible to a lower-than-intended input voltage than the old router. Anyway, the voltage drop over the length of the 25 meter long cable...