If you own the small EdgeRouter ER-X from Ubiquity, you may have wondered whether the “12V” indication printed on the back of the power connector should be taken particularly seriously.
In short: no. Ubiquity states in the User Guide of the ER-X that between 9 and 24 volts are possible (apart from the passive PoE capability).
We tested it: a 24 volt power supply does not actually kill the small router. It runs perfectly. The 12 volt power supply also works obviously but also a 5 volt power supply with 2 amps, which you have lying around, does its job. The range of possible voltages is therefore quite large. Whether you should flash firmware with a 5 volt power supply is an open question, but for normal operation and if you don’t have any other power supply at hand, it is sufficient.
So: the voltage range for the ER-X is very flexible. From 5 volts to 24 volts, it seems to get along with any power supply. This knowledge can be helpful if the original power supply unit dies and you need a replacement quickly.