As the current stormy weather caused quite lots of power interruptions, I wondered if the lower internet connectivity quality in the last months was not due to the fact that the MPOE had no UPS backup.
Checking this on my logs, a correlation on poor internet connectivity and ADSL Modem moved to the MPOE, existed. Knowing this, I finally got a UPS and connected the MPOE's power supply to this UPS. The fact that many people in france actually use electric heating reduces the voltage of the current power-grid down to 200V instead of regular 230V.
The UPS is nothing fancy or big, just small enough to fit onto the MPOE (check this out), and configuration-less operations.