suddenty can't access a certain IP range anymore!?

Hi, we've got the following subnet mask for our network, so from to

Everything used to work correctly but after an electricity outage devices with IP from to can't connect to devices having an 192.168.0.x address!? But those devices can be connected to if an .0.x address is manually given to a laptop, for example.

What could the reason for this be!?

The switches seem to be configured correctly ... in any case, it DID work before ...
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Leroy LuffHead of IT & DIgitalCommented:
My best guess is that your firewall or a managed switch has lost its setting in the power outage. Make sure both of those have the correct subnet masks configured.

Sometimes when you do configurations on Cisco switches they can be applied but not saved to the ROM. So the 1st time they reboot they revert back.

Have you configured VLANS for the different ranges on any device or is it free for all?

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Double check the devices on the 192.168.0.x subnet, if they have a subnet mask of then you won't get any response from them if you try to connect from 192.168.1+.x

If using Cisco enterprise switches or similar, it's possible that when the power was disrupted, they lost their active config, and reverted to the config that's stored on the local flash.

If you make changes on the switch and don't save them with write memory (or equiv) then it will lose those changes on reboot.
Mr TorturSystem EngineerCommented:
+1 for the switch loose config theory, it seems to me that the issue is more about the routing table of the switch.
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XeronimoAuthor Commented:
I'm using 3COM switches ... the switches have a 192.168.2.x address with a subnet mask. Yet they can't ping the 192.168.0.x device ... although they should be able to do that, right? Where else would this be configured?

As for the .0.x device it has a .248 netmask as far as I know ... can't verify myself ... I have to solve this remotely right now ... thanks!
XeronimoAuthor Commented:
as for the routing tables, just to be sure ... where would the, with netmask need to be routed to? I think I remember seeing that there.
XeronimoAuthor Commented:
Leroy: we have 2 VLANs but those devices are all on the same VLAN
Leroy LuffHead of IT & DIgitalCommented:
The switch is definitely your problem here or your firewall.

I would def take a look at the switch config. Perhaps place it on the .0 range with a .248 subnet.
XeronimoAuthor Commented:
the switch in question had indeed lost its configuration (or it hadn't been saved ...), once that was corrected everything worked fine again
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