Expecting that all of the devices have the right subnet-mask then traffic should not reach the Firewall. Traffic should stay on the L2 domain.
That being said:
- Do the PC and Server have the IP address configured statically or is via DHCP?
Next time the issue happens Check
- Try to ping the Firewall from the PC and Server
- Check the ARP table of the PC/Server
- Interface status of the switches
sh interfaces fastEthernet x/x switchport
sh interfaces fastEthernet x/x status err-disabled
- The MAC address table of the switches
show mac address-table interface fastEthernet x/x (Make sure you see the MAC address of the PC/Server on the right ports)
Hope this helps,
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