I am having a problem that I do not quite understand with my network setup.
I have four switches on the network: Switch A is a managed network switch which is connected to the PC router -- it is set to its factory defaults with no advanced configuration. Switch B is an unmanaged network switch which is connected to the phone router. Switch C & Switch D are both configured with VLANs 1 and 10. Ports in each VLAN on both Switch C and Switch D are connected to ports on switches A and B as follows:
Switch C port 24 (VLAN 10) -> Switch A port 48
Switch C port 23 (VLAN 1) -> Switch B port 1
Switch D port 24 (VLAN 10) -> Switch A port 47
Switch D port 23 (VLAN 1) -> Switch B port 2
VLAN 1 Network: 10.10.20.0/24
VLAN 10 Network: 10.20.30.0/24
I am only using the VLAN functionality to logically separate ports on Switches C & D into two different broadcast domains. The Switches are configured to untag the packets on egress, so the upstream switches (A & B) should have no concept of the VLANs.
The problem I am having is that Switch C and Switch D are unable to connect to Switch A simultaneously, whereas both are able to connect to Switch B without issue.
Can anyone provide insight on why this could be?