Bizarre problem

[Mark_AV]

Morning,

So we had an electrician change a fuse yesterday and it dropped a lot of our servers off the network briefly...
That all sorted but we have an odd problem with about 60% of users in the building.....none of them could get back on the domain.

We have switches and each network cable runs to the port then into the switch for network access.
Users have static IP addresses

If any users swapped network cable (whilst leaving in the same port, just switching computer end) they could get back on.
Switch cable back - can't get on.

So 60% of users in the building have had to swap network ports with the other.
WHY?

DNS flush doesn't work
rejoin domain doesn't work
network reset doesn't work

Please help

 

[Mark_AV]

OK so i think once you reboot it is effecting everyone?!

 

[Corday]

Try this as a test with one unit: Rejoin a Computer from a Domain In One Easy Step! -- Microsoft Certified Professional Magazine Online

 

[Mark_AV]

That isn't the issue.
When we had some fuse changed something happened

A PC connected to a port, then the patch panel to the switch.
At the point of the issue, nobody can use their existing port - once you swap any user to any other port - it's fine....bar a few.
Once you put any user back in their original port - unidentified network.
So we just swapped all users network cables with another - left the ports - sees the domain no problem

Never seen anything so strange.

Any other ideas?

 

[Corday]

Was the power down for the whole building, the network or what? Most modern facilities use breaker panels so that's what confuses me. Ordinarily I'd say it's the port, but of course the anomaly seems to be other users can use the "blown" port(s). I don't think your answer is here How to Fix an Unidentified Network Error in Windows but take a look anyway

 

[Mark_AV]

Hard to say, as my machine is unaffected, so not everyone.
Have tried all options in that article and still the ONLY thing that works is swapping to a different port in the switch.
Mind blown.

 

[Corday]

If you're the only Admin, give a person temporary Admin rights and see if they don't have the problem.

 

[Fred Garvin]

Hard to say, as my machine is unaffected, so not everyone.
Have tried all options in that article and still the ONLY thing that works is swapping to a different port in the switch.
Mind blown.

Are you using managed switches and have you tried power cycling them or shutting them down for a few minutes? It sounds like cached info stuck in the switch or a bad ARP table. I have some HP managed switches that run into a similar problem occasionally.

 

[Mark_AV]

I think it's gonna be power cycling the switches, it's just finding a good time to do it! will have to be out of hours.
Thanks