There could a couple of problems that would be the reason that the UPS is not able to power your equipment.
1. You have exceeded the output limits of the UPS. If the power demand from all the devices exceed the UPS' capacity. The model that you indicate should be able to power a total of 1000 watt load for about a few minutes. If should be able to power your computer, monitor, modems/routers easily, but if you have a laser printer attached, it will not be able to sustain the demands of the printer. Try removing any heavy loads like printers and see if this will work.
2. The battery in the UPS needs to be replaced. The battery in a UPS is only good for a few years. After a while it needs to be replaced because after a while it is not able to supply the needs of the UPS. If the battery is more than 2-3 years old it should be replaced.
Answers & Comments
There could a couple of problems that would be the reason that the UPS is not able to power your equipment.
1. You have exceeded the output limits of the UPS. If the power demand from all the devices exceed the UPS' capacity. The model that you indicate should be able to power a total of 1000 watt load for about a few minutes. If should be able to power your computer, monitor, modems/routers easily, but if you have a laser printer attached, it will not be able to sustain the demands of the printer. Try removing any heavy loads like printers and see if this will work.
2. The battery in the UPS needs to be replaced. The battery in a UPS is only good for a few years. After a while it needs to be replaced because after a while it is not able to supply the needs of the UPS. If the battery is more than 2-3 years old it should be replaced.
Hope this help you.