I just installed and configured my brand new Wifi Extender RE700X, first it was broadcasting a Wifi 5 (AC) signal, but somehow after a couple of days it automatically switched to a Wifi 6 (AX) signal...

@jorgeguerrerom Did you try to manually assign Extender's DNS same as your router's ones? Seems like your primary DNS is configured as the same IP as your router and no secondary DNS, maybe you need...