My network runs through the electrical wiring of the house and is organised as such:

  • Groundfloor:

    • an ADSL+network switch, using DHCP (address :
    • (Mac) PCs connected via an electrical adapter (model: D-Link DHP-200) (1 per PC)

  • First Floor:

    • 1 switch (8 ports) connected via an electrical adapter (model: D-Link DHP-200) (address unknown)
    • 2 Mac PCs connected (via RJ45 network wires) to that router using DHCP

The Problem

On the first floor, file transfers between PCs are fast and perfect. But if I try to transfer files from or to a computer on the ground floor, the speed is slow and eventually the transfer dies out.

The Question

So I suspect the 1st floor switch is creating some kind of barrier (firewall?) preventing external PCs from accessing the PCs it is connected to?

Am I right and if so, how could I disable that barrier?


A switch should only pass traffic transparently. It doesn't have an IP address and shouldn't be doing anything more than passing traffic along.

It's possible you could be having hardware issues with the switch itself, but, as a rule, there really shouldn't be any kind of configuration to speak of on most consumer switches.

  • Managed switches have IP addresses for the management interface. – MDMarra Jun 8 '10 at 10:53
  • Sure, but it's kind of outside the realm of consumer home networking equipment, which is why I made that distinction. – jslaker Jun 21 '10 at 4:01

Have you tried a direct connection from one PC through the electrical adapter without the router on the first floor? If speed is fast then, the router (what vendor/model?) might be the cause. It's possible, that it must fragment all IP packets (other MTU-size) and the buffer gets overflowed and retransmits must be made. You can check this using Wireshark on both sides of the "electric wire".

As you do not write what router you use, it's hard to guess the (default?) configuration made.

  • sorry i 'm wrong: on first floor, it's not a router, it's a switch. Still, could a switch impair the lan connection? – pixeline Dec 15 '09 at 8:31
  • I finally did the check you suggested: the speed is, indeed, fast, so it's the switch that creates the slowdown. Any idea why ? – pixeline Dec 23 '09 at 17:50
  • Maybe it's an old Switch which only supports 10/100Mbit? A switch always outputs the incoming singal to all ports. Maybe there are too many collisions? Is this switch really a no-name brand? – Scoregraphic Dec 24 '09 at 6:40

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