NIC / 3com Switch, 10Mbps but not 100Mbps?

Question

My computer hv been working well with the 3Com Switch for quite a long time. Suddenly one day it just can't connected to the LAN, after several trial and error, found out if I change the NIC's link speed to 10Mbps it works, but failed if I changed it back to 100Mbps or Auto Detect Mode. The same is true if I change the link speed of the switch port. Could there any one guru explain to me what it is going on? how can I solve it, I wanna connected at 100Mbps rather than 10Mbps. Thank you for any help.

I tried other NICs, too, but to no avail.

Hi NYC-Brooklyn, It's nothing to do with the internet speed, it's the connection between my computer and my switch, where other computers are connected. Other computer on the network don't have the same problem.

Hi NYC-Brooklyn, It's nothing to do with the internet speed, it's the connection between my computer and my switch, where other computers are connected. Other computer on the network don't have the same problem. Thanks

Hi Muon,
It's a heterogenous network where there's printer servers, laptops and desktops, so definitely there's 10MHz devices, as well as 100MHz's. Thanks

Hi Muon,
Let me try your method later.
This is not an easy job since it's a fully-occupied 48-port switch. Thanks

Hi bob g,
Yes, I do. no use. Thanks

Answer 1

Do you have any other 10MHz devices connected to the same hub? If you do, the whole subnet is pulled down to 10MHz.

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My previous answer does not explain why you cannot auto detect the network speed. Did you have those 10MHz devices connected when you didn't need to switch down the speed manually? (You might think you have 100MHz, but you were actually doing only 10.)

Try to remove all other devices and see if you can do 100. Then add them back to the network one by one.

If you cannot get 100 after removing all other devices, you probably have a bad hub.

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I thought you mistaken a hub from a switch. It looks like you do have a switch. Then, you may be able to mix 100 and 10MHz devices and still perform 100MHz for some. (depending on manufacturer?)

The debugging method above still hold.

Answer 2

Have you tried a different port on the switch to see if you have the same results?

It could be a faulty port. Have you tried resetting the switch to see if that helps?

Try the nic card with the problem in a different port and try a different nic in the port with the problem to try and determine which end is causing the difficulties.

Answer 3

I know on mine it says 100mps too but ot matters
what connectin u have like T1
http://www.bandwidthplace.com/speedtest/
ur speed.