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New Switch causing various PC’s to knock off LAN

Frequent Advisor

New Switch causing various PC’s to knock off LAN

Hello all, we have an urgent issue and need some advice.


I have attached a quick Network Diagram for you review, the network is extremely simple. 


One main HP 4208vl located in the Comms Room.

Two HP 2824 Switch’s located in the Server Room.

Two old HP 2524 100mb switch’s in the Server room but only used for printers.


All Switches hooked up via Trunk’s to Main Switch.


All switches have STP enable.


All Switches have latest Firmware’s.


And that’s it, nothing else configured.


So first question is having I missed anything/should I be configuring anything else, it’s a typical Windows Network with a mixture of old and new PC’s.  All servers are patched into the 2824 gb switch’s and these have various trunks to the main 4208.


All PC’s are HP, new and old.




Only occurs when users turn on their pc.


Every day around 4 – 5 users will call and say they cannot access the LAN.  The only fix we can do is to DISABLE THE NIC, then RE-ENABLE it, this get the user up and running immediately.  By asking the user to reboot the pc does not fix the issue, a repair does not fix it, ip release-renew does not fix it, replacing the nic cable does not fix it.  It also only happens when powering on the pc.


The only fix is to Disable, then Re-Enable the Nic.


It only happens when powering on the pc, once its on it is fine.


I’ve checked the logs on the switch and I can see that one of the pc’s did report “Block by STP” then once we got the user to disable then re-enable the nic the log reported back online. However there are hundreds reporting “Blocked by STP” is this right?  We don’t know exactly what is plugged into every port.


Has anyone come across anything like this; any help would be good at this stage.  


This has only started to happed over the last two weeks since we have replaced the old HP 400m to a HP H208vl Switch.