I have three connections in my lab. One for the fan, one for charging my laptop and one ethernet connection for my laptop. When the power suddenly goes off sometimes, the fan stops working and my laptop stops charging but the internet connection is still intact. How is this possible?

 

Does the entire world lose power?

 

Impossible to say without knowing where in the world you're located and what you mean by Internet connection.

If it's dialup, our phone companies provide backup power for POTS.

If you're using cellular, towers have battery backup.

 

I'm located in India. Sometimes, when power cut occurs, the connection to the fan works but the power to the internet connection using LAN cable and the charging port is lost. In other cases, the power to the charging port and fan is lost but the power to internet using the LAN cable is still there. One end of ethernet cable is connected to my laptop and other end goes to an ethernet cable coupler housed in a box.

 

Sounds like somewhere in this process is a random number generator that decides which one thing will continue to run, assuming that at other times the fan and internet connection are lost but the charging port keeps working.

 

I'm located in India. Sometimes, when power cut occurs, the connection to the fan works but the power to the internet connection using LAN cable and the charging port is lost. In other cases, the power to the charging port and fan is lost but the power to internet using the LAN cable is still there. One end of ethernet cable is connected to my laptop and other end goes to an ethernet cable coupler housed in a box.

power to internet? Is this a POE line?
I would not expect POE lines in India but rather normal Ethernet connections..
Ethernet connections/lan cables are typically just data connections and not power..

Some can be connected to a POE injector which will apply voltage over the lines to allow it to power remote devices like cameras or phone systems,etc....


I "think" all you are seeing is that your ethernet connection is staying active because its maybe got a UPS/battery backup or something and the laptop battery is keeping the yellow/green LEDs at the internet lan cable jack on.

But without a complete/detailed wiring diagram (system schematic) we do not know whats powered by what and what has a battery backup or not and nor do we know how/which circuits of power you are losing,etc...