Could it be the UPS?

It looks like our aging UPS is failing, and when doing so, sometimes cuts the power to all the devices is serves. Indecently, this exactly is what UPS is supposed to prevent, but for its defense one is not supposed to run a UPS without replacing its rechargeable battery for... 10 years. We decommissioned this aging UPS, which might have been the cause for the recent periods downtime.