@Intrudaz 

Hey and Welcome

When you say it gets disconnected, are the lights still flashing on the port of the switch?     Im guessing you discover this issue as the connected PCs / Laptops lose internet access?

If so its more than likely not the switch, rather the DHCP or the router providing it.   The switch literally just moves the data along.

Any more info you can give us would help!

  @Philbert  Hi! Except for the power light indicator, all the other lights go off. It's like the ports stop working.

The TL-SG105 switch received its connection from another L2 TP-Link Switch(TL-SG108E). The connection is set up as follows:

ISP Router >> TL -SG108E >> TL -SG105