I recently purchased a Bery AX router and I'm having the same issue. I'm trying to use a xiaomi 65w PD gan charger, and it does not power the router. I've tried different cables with the same result. Oddly, if i plug and unplug the router repeatedly, sometimes it seems to work, about 1/10 the time. When it negotiates power, it works perfectly fine.
Try the 18W regular power brick that used to come inside the iPhone box few years back. It works perfectly fine and Iām using since last 1 year with out any issue