@Nisar https://openwrt.org/toh/views/toh_fwdownload?dataflt%5BBrand*%7E%5D=TP&dataflt%5BModel*%7E%5D=Archer+C20 (change the filter to whatever is appropriate for your model)

I'm expriencing similar behaviour. I recently got a new Mac, and am connecting it over ethernet (everything else is on WiFi, and always has been). I have noticed, if that Mac sleeps, or I unplug it...