This is all theory as I haven't got a router to test.
Looking at the attached /embedded drawing, PC1 needs to talk to PC2.
Switch 1 has ports 2-23 configured for Switchport mode access, ports 1 & 24 are trunks.
Switch 2 has ports 1-23 configured for switchport mode access, switchport access vlan 2, port 24 is trunk.
My question is, do the switches need to have both interface vlan 1 and interface vlan 2 configured in their config?, or does switch 1 only need interface vlan 1 as none of the ports will be used for vlan 2?
I currently have all switches configured with both.