Help needed with switch!

Ok, I have a weird problem...
I live in a dorm, where me and my roommate share wired Internet connection through a switch(because there is only one main cable)...
Internet is allowed by MAC addresses...

Everything was fine for a year...but now, suddenly, we can't both get to the Internet at once...only on of us can make the connection - and it doesn't seem to matter witch one, beside who gets to make the connection first...

I have tested the switch for malfunctions, but everything works fine on an other location(like at home)...

Local IT-guy(who messes with dorm connections, etc..), didn't knew what to say to our problem...

Help me, please...

Don't you just love college internet

I'd try swapping out the switch just to be sure. Diagnostics aren't always accurate.

Well, I'm pretty sure it's not the switch, because at home I'm sharing internet among two computers in the same way - and there it's working like charm...I mean the same switch

What do you mean by the "Internet is allowed by MAC addresses" statement? It sounds like you might have a limit to the number of MAC addresses allowed on that port. Or, you have an authentication problem with whatever is granting network access.

Does the college restrict the numbers of computers allowed per dorm?

I mean if we made a contract/request for internet connection, we had to include our MAC addresses...

Does the college restrict the numbers of computers allowed per dorm?

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Not to my knowledge...

It sounds like you might have a limit to the number of MAC addresses allowed on that port. Or, you have an authentication problem with whatever is granting network access.

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Local network administrator says that everything is fine on his side...I presume that also means that there is no limit to MAC addresses per port...

Do both computers get assigned a proper IP address?

Connect both machines and let us know what IP addresses they show.

The problem is likely that DHCP on the switch is interfering with DHCP on the school's network. I would try using a hub rather than a switch. I don't know about your school, but when I was at college they gave us hubs for the dorms since two people couldn't really be expected to use one internet connection.

If we are talking about an actual Ethernet switch here, then there can be no DHCP conflict with that device. A switch or hub do not supply DHCP. Now, a router on the other hand can.

Is this switch an actual switch or are you talking about a router, Nielander? The make/model of the unit in question would be helpful if you are unsure.

Connect both machines and let us know what IP addresses they show.

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Ok, my computer tells me this:

Connection status:
Address type: Assigned by dhcp
IP address: 192.168.99.173

Roomate's

Connection status:

Limited or no connectivity
(under details he gets random IP)

But if my roommate would have connected first, things would be reversed...

Is this switch an actual switch or are you talking about a router, Nielander?

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No, it's a switch, I sure of it...but for some reason there is no model name on it...only writings: 5-port Switch 10/100Mbps ETHERNET

That's what I suspected. And the college IT guy was clueless?? That does not bode well...

It sure seems like there is some sort of MAC filtering going on off that port. In other words, once an IP is established, the other computer(s) trying to connect will not receive IP addresses and are essentially denied access to the LAN.

Once you have one computer's connection established do any other machines (not just your roommate's) also not receive an IP address? Have you been doing any MAC spoofing on either of your computers?

One thing you could try - hook up a router, then once the router has an IP address, connect both computers to the router. Essentially, treat the college like an ISP like you would at home. Double NAT is never fun, but without getting campus IT involved, you may be stuck. From what I can tell with the info provided so far, the issue is most likely on their end.

By the way, welcome to the forum!