In the actual Keenetic models (KN-xxxx) the voltage of the USB port has been raised to 5.20V and the current on USB 2.0 is now the same as the USB 3.0 standard (i.e. 900 mA) plus smoothing capacitors are installed. The said power should be sufficient for most modern USB modems.
We design all current Keenetic KN-xxx models so that with a current of 1A, the voltage is at least 5V. This is true for both USB 2.0 and USB 3.0 ports.
With no load, the voltage should be between 5.15V and 5.20V.
The current can also be greater than 1 A, but this may cause the voltage to drop below 5 V.