Connection working with router but not with switch [closed]

        This is a very simple and stupid problem but I can't get around it.

I am having an issue with one connection from a distribution-layer switch to an access-layer switch. I hope someone can point me in the right direction on how to troubleshoot this problem, since I am completely stuck. I hope the question is clear. The setup In my setup, there is a distribution-layer, 24-port, TPLink switch in a rack that gives internet access to four offices. All ports seem to be working fine. One of the offices is far away. There is a CAT5e Ethernet cable of about 80m that runs from the switch on the rack to an 8-port switch at the office. There are two computers and an IP phone in this office connected to that switch. The issue As it is, the connection between the racked switch and the 8-port switch doesn't work. I've tried all the 24 ports of the first switch (which I'm sure work fine) and tried replacing the 8 port switch. Nothing works. There is no activity light in the connected ports. Connecting a single device directly to the 24-port switch works. So the cable doesn't seem to be the problem. The only thing that solved the issue is replacing the 8-port switch with a cheap router (connected as a switch, with all cables connected to LAN ports, WAN port unconnected). That works just fine. So please, does anyone know why would the connection work with a router but not with a switch? I am completely perplexed and would welcome any suggestions. In any case, should I replace the 24-port switch? I sense the problem will still persist but is something I could try. Thanks everyone.